Method for producing and purifying 2,3,3,3-tetrafluoro-1-propene

ABSTRACT

The present invention concerns a method for purifying 2,3,3,3-tetrafluoro-1-propene (1234yf) from a first composition comprising 2,3,3,3-tetrafluoro-1-propene and at least one of the compounds chosen from the group consisting of 1,1-difluoroethane (152a), chloropentafluoroethane (115), and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) said method comprising the steps consisting of: a) bringing said first composition into contact with at least one organic extractant in order to form a second composition; b) extractive distillation of said second composition in order to form (i) a third composition comprising said organic extractant and said at least one of the compounds chosen from the group consisting of 1,1-difluoroethane (152a) chloropentafluoroethane (115), and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); and ii) a stream comprising 2,3,3,3-tetrafluoro-1-propene. The invention also concerns a method for producing and purifying 2,3,3,3-tetrafluoro-1-propene.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage application of InternationalApplication No. PCT/EP2016/080946 filed on Dec. 14, 2016, which claimsthe benefit of French Patent Application No. 1563166 filed on Dec. 23,2015, the entire content of all of which is incorporated by referenceherein.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a process for purifying2,3,3,3-tetrafluoro-1-propene. The invention also relates to a processfor producing and purifying 2,3,3,3-tetrafluoro-1-propene.

Technological background of the invention Hydrofluorocarbons (HFCs) andin particular hydrofluoroolefins (HFOs), such as2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), are compounds known fortheir properties as coolants, heat-transfer fluids, extinguishers,propellants, foaming agents, swelling agents, gaseous dielectrics,polymerization medium or monomer, support fluids, agents for abrasives,drying agents and fluids for power production units. HFOs have beenidentified as desirable alternatives to HCFC on account of their low ODP(ozone depletion potential) and GWP (global warming potential) values.

Most of the processes for manufacturing hydrofluoroolefins involve afluorination and/or dehydrohalogenation reaction. These reactions areperformed in the gas phase and generate impurities which consequentlyneed to be removed to obtain the desired compound in a sufficient degreeof purity for the targeted applications.

For example, in the context of producing 2,3,3,3-tetrafluoro-1-propene(HFO-1234yf), the presence of impurities such as1-chloro-3,3,3-trifluoro-1-propene (1233zd),1,3,3,3-tetrafluoro-1-propene (1234ze) and 1,1,1,3,3-pentafluoropropane(245fa) is observed. These impurities are isomers of the main compoundsthat are desired to be obtained via the process for producing2,3,3,3-tetrafluoro-1-propene, besides the latter, i.e.2-chloro-3,3,3-trifluoro-1-propene (1233xf) and1,1,1,2,2-pentafluoropropane (245cb). Given the respective boilingpoints of 1-chloro-3,3,3-trifluoro-1-propene (1233zd),1,3,3,3-tetrafluoro-1-propene (1234ze) and 1,1,1,3,3-pentafluoropropane(245fa), they may accumulate in the reactor and thus prevent theformation of the products of interest.

Purification of this type of reaction mixture may be performed viavarious techniques known from the prior art, for instance distillation.However, when the compounds to be purified have boiling points that aretoo close or when they form azeotropic or quasi-azeotropic compositions,distillation is not an efficient process. Extractive distillationprocesses have thus been described.

EP 0 864 554 discloses a process for purifying a mixture comprising1,1,1,3,3-pentafluoropropane (245fa) and1-chloro-3,3,3-trifluoro-trans-1-propene (1233zd) by distillation in thepresence of a solvent with a boiling point of greater than that of1-chloro-3,3,3-trifluoro-trans-1-propene.

WO 03/068716 discloses a process for recovering pentafluoroethane from amixture comprising pentafluoroethane and chloropentafluoroethane bydistillation in the presence of hexafluoropropene.

WO 98/19982 also discloses a process for purifying 1,1-difluoroethane byextractive distillation. The process consists in placing an extractingagent in contact with a mixture of 1,1-difluoroethane and vinylchloride. The extracting agent is chosen from hydrocarbons, alcohols andchlorocarbons with a boiling point of between 10° C. and 120° C. Asmentioned by WO 98/19982, the selection of the extracting agent mayprove to be complex depending on the products to be separated.

WO 2009/105521 discloses a process for purifying by azeotropicdistillation z mixture comprising 1,3,3,3-tetrafluoropropene and2,3,3,3-tetrafluoropropene. There is thus still a need to develop aparticular process for purifying 2,3,3,3-tetrafluoro-1-propene.

SUMMARY OF THE INVENTION

In a process for producing 2,3,3,3-tetrafluoro-1-propene, the choice ofparticular operating conditions makes it possible to promote thepresence of certain impurities or of isomers thereof. The presence ofimpurities such as 1,3,3,3-tetrafluoro-1-propene (1234ze) may beobserved, as may that of 1-chloro-3,3,3-trifluoro-1-propene (1233zd) and1,1,1,3,3-pentafluoropropane (245fa). These impurities may derive fromside reactions induced by intermediate compounds produced during theproduction of 2,3,3,3-tetrafluoro-1-propene, and may have physicalproperties such that the removal thereof may prove to be complex. Thepresent invention allows the production of 2,3,3,3-tetrafluoro-1-propenein improved purity.

According to a first aspect, the present invention provides a processfor purifying 2,3,3,3-tetrafluoro-1-propene (1234yf) using a firstcomposition comprising 2,3,3,3-tetrafluoro-1-propene and at least one ofthe compounds chosen from the group consisting of 1,1-difluoroethane(152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), said process comprisingthe steps of:

-   -   a) placing said first composition in contact with at least one        organic extracting agent to form a second composition;    -   b) extractive distillation of said second composition to form:        -   i) a third composition comprising said organic extracting            agent and said at least one compound chosen from the group            consisting of 1,1-difluoroethane (152a),            chloropentafluoroethane (115) and            trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); and        -   ii) a stream comprising 2,3,3,3-tetrafluoro-1-propene;    -   c) recovery and separation of said third composition to form a        stream comprising said organic extracting agent and a stream        comprising said at least one compound chosen from the group        consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); preferably, the        stream comprising said organic extracting agent may be recycled        into step a).

Preferably, the stream comprising 2,3,3,3-tetrafluoro-1-propene formedin step b) is recovered. This stream may be optionally purified toachieve a degree of purity suitable for particular commercialspecifications.

Preferably, said organic extracting agent may have a boiling point ofbetween 10 and 150° C.

According to a preferred embodiment, the first composition comprises2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one of the compounds chosenfrom the group consisting of 1,1-difluoroethane (152a) andchloropentafluoroethane (115) and the third composition comprises saidorganic extracting agent, trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E)and optionally or not at least one of the compounds chosen from thegroup consisting of 1,1-difluoroethane (152a) andchloropentafluoroethane (115); step c) being the recovery of said thirdcomposition and separation between, on the one hand, said organicextracting agent and, on the other hand,trans-1,3,3,3-tetrafluoro-1l-propene (1234ze-E) and optionally or not atleast one of the compounds chosen from the group consisting of1,1-difluoroethane (152a) and chloropentafluoroethane (115).

According to a preferred embodiment, said organic extracting agent is asolvent chosen from the group consisting of hydrocarbon,halohydrocarbon, alcohol, ketone, amine, ester, ether, aldehyde,nitrile, carbonate, thioalkyl, amide and heterocycle; or said organicextracting agent is difluorodiethylsilane, triethylfluorosilane orperfluorobutanoic acid; preferably from the group consisting of amine,ether, ketone, ester, alcohol, aldehyde and heterocycle.

According to a preferred embodiment, said organic extracting agent has aseparation factor S_(1,2) of greater than or equal to 1.1, saidseparation factor being calculated by the formulaS_(1,2)=(γ_(1,S)*P1)/(γ_(2,S)*P2) in which

-   -   γ_(1,S) represents the activity coefficient of        2,3,3,3-tetrafluoro-1-propene in said organic extracting agent        at infinite dilution;    -   P1 represents the saturating vapor pressure of        2,3,3,3-tetrafluoro-1-propene;    -   γ_(2,S) represents the activity coefficient of said at least one        compound consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic        extracting agent at infinite dilution, advantageously the        activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene        (1234ze-E) in said organic extracting agent at infinite        dilution;    -   P2 represents the saturating vapor pressure of said at least one        compound consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), advantageously        the activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene        (1234ze-E);    -   advantageously, the separation factor is greater than or equal        to 1.2, preferably greater than or equal to 1.4, more        preferentially greater than or equal to 1.6, in particular        greater than or equal to 1.8, more particularly greater than or        equal to 2.0.

According to a preferred embodiment, said organic extracting agent hasan absorption capacity C_(2,S) of greater than or equal to 0.20, saidabsorption capacity being calculated by the formula C_(2,S)=1/(γ_(2,S))in which γ_(2,S) represents the activity coefficient of said at leastone compound consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) in said organic extracting agent at infinite dilution,advantageously, the activity coefficient oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); advantageously, theabsorption capacity C_(2,S) is greater than or equal to 0.40, preferablygreater than or equal to 0.60, more preferentially greater than or equalto 0.80, in particular greater than or equal to 1.0.

According to a preferred embodiment, said first composition is anazeotropic or quasi-azeotropic composition comprising2,3,3,3-tetrafluoro-1-propene and said at least one compound chosen fromthe group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), preferably an azeotropic or quasi-azeotropic compositioncomprising 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or not atleast one compound chosen from the group consisting of1,1-difluoroethane (152a) and chloropentafluoroethane (115).

According to a preferred embodiment, said organic extracting agent ischosen from the group consisting of ethylamine, isopropylamine, diethylether, ethoxyethene, dimethoxymethane, n-propylamine, methyl t-butylether, diethylamine, propanone, methyl acetate, isobutanal,tetrahydrofuran, isopropyl formate, diisopropyl ether,2-ethoxy-2-methylpropane, ethyl acetate, butanone, diethoxymethane,isopropyl acetate, 3-pentylamine, 2-methoxyethanamine, tert-butylacetate, dioxane, 3-pentanone, 1,1-diethoxyethane, 2-pentanone,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,sec-butyl acetate, 4-methyl-2-pentanone, 1,2-diaminoethane, 1-methoxy2-propanol, diethyl carbonate, n-butyl acetate, 1-ethoxy-2-propanol andhexanal; advantageously, said organic extracting agent is chosen fromthe group consisting of ethylamine, isopropylamine, diethyl ether,dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, butanone, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal; preferably, said organic extractingagent is chosen from the group consisting of ethylamine, isopropylamine,diethyl ether, dimethoxymethane, n-propylamine, diethylamine,diisopropyl ether, 2-ethoxy-2-methylpropane, diethoxymethane, isopropylacetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate,dioxane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal.

Preferably, the stream comprising 2,3,3,3-tetrafluoro-1-propene formedin step b) is recovered and is freed of at least one of the compoundschosen from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), preferably freed of trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E).

According to a preferred embodiment, said process comprises, prior tostep a), the following steps:

-   -   i′) use of a composition comprising        2,3,3,3-tetrafluoro-1-propene, impurities with a boiling point        below the boiling point of 2,3,3,3-tetrafluoro-1-propene, and at        least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), and optionally        heavy impurities;    -   ii′) distillation of said composition from step i) to remove, at        the top of the column, impurities with a boiling point below the        boiling point of 2,3,3,3-tetrafluoro-1-propene and to form a        first stream comprising 2,3,3,3-tetrafluoro-1-propene and at        least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), and optionally        heavy impurities, recovered at the bottom of the distillation        column;    -   iii′) optionally, distillation of said first stream recovered at        the bottom of the distillation column in step ii′) to recover,        at the top of the column, a second stream comprising        2,3,3,3-tetrafluoro-1-propene and at least one compound chosen        from the group consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), and, at the        bottom of the distillation column, a stream comprising the heavy        impurities;    -   said at first stream recovered in step ii′) or said second        stream recovered in step iii′) corresponds to said first        composition used in step a).

The heavy impurities may contain, for example,1,1,1,3,3,3-hexafluoropropane (236fa), 1,1,1,2,3,3-hexafluoropropane(236ea), 1,1,1,2,3,3,3-heptafluoropropane (227ca),cis-1,3,3,3-tetrafluoro-1-propene (1234ze-Z), and dimers or trimersderived from one of the compounds present in the composition or thestream under consideration, for example C4 or C5 hydrocarbons such ashexafluorobutene (1336), heptafluorobutene (1327), octafluorobutane(338), nonafluoropentene (1429) or heptafluoropentene (1447).

According to a second aspect of the present invention, a process forproducing 2,3,3,3-tetrafluoro-1-propene is provided. Said processcomprises the steps of:

-   -   A) fluorination in the presence of a catalyst of a compound of        formula CX(Y)₂—CX(Y)_(m)—CH_(m)XY (I) in which X and Y        independently represent H, F or Cl and m=0 or 1; and/or        fluorination in the presence of a catalyst of a compound of        formula (CX_(n)Y_(3-n))CH_(p)X_(1−p)CH_(m)X_(2-m) (II) in which        X is, independently of each other, Cl, F, I or Br; Y is,        independently of each other, H, Cl, F, I or Br; n is 1, 2 or 3;        and m is 0, 1 or 2; and p is 0 or 1;    -   B) recovery of a stream comprising 2,3,3,3-tetrafluoro-1-propene        and at least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E);    -   C) implementation of the process for purifying        2,3,3,3-tetrafluoro-1-propene according to the present invention        using the stream recovered in step B).

According to another aspect, the present invention provides acomposition comprising 2,3,3,3-tetrafluoropropene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and an organic extractingagent with a separation factor S_(1,2) of greater than or equal to 1.6,said separation factor being calculated by the formulaS_(1,2)=(γ_(1,S)*P1)/(γ_(2,S)*P2) in which γ_(1,S) represents theactivity coefficient of 2,3,3,3-tetrafluoropropene in said organicextracting agent at infinite dilution, P1 represents the saturatingvapor pressure of 2,3,3,3-tetrafluoropropene, γ_(2,S) represents theactivity coefficient of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E)in said organic extracting agent at infinite dilution, P2 represents thesaturating vapor pressure of trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E); preferably, said organic extracting agent has an absorptioncapacity C_(2,S) of greater than or equal to 0.8, said absorptioncapacity being calculated by the formula C_(2,S)=1/(γ_(2,S)) in whichγ_(2,S) represents the activity coefficient oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organicextracting agent at infinite dilution.

According to a preferred embodiment, for any of the above compositions,the organic extracting agent may be chosen from the group consisting ofethylamine, isopropylamine, diethyl ether, ethoxyethene,dimethoxymethane, n-propylamine, methyl t-butyl ether, diethylamine,propanone, methyl acetate, isobutanal, tetrahydrofuran, isopropylformate, diisopropyl ether, 2-ethoxy-2-methylpropane, ethyl acetate,butanone, diethoxymethane, isopropyl acetate, 3-pentylamine,2-methoxyethanamine, tert-butyl acetate, dioxane, 3-pentanone,1,1-diethoxyethane, 2-pentanone, trimethoxymethane, n-pentylamine,1,3-dioxane, 3,3-dimethyl-2-butanone, sec-butyl acetate,4-methyl-2-pentanone, 1,2-diaminoethane, 1-methoxy 2-propanol, diethylcarbonate, n-butyl acetate, 1-ethoxy-2-propanol and hexanal;advantageously, said organic extracting agent is chosen from the groupconsisting of ethylamine, isopropylamine, diethyl ether,dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, butanone, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal; preferably, said organic extractingagent is chosen from the group consisting of ethylamine, isopropylamine,diethyl ether, dimethoxymethane, n-propylamine, diethylamine,diisopropyl ether, 2-ethoxy-2-methylpropane, diethoxymethane, isopropylacetate, 3-pentylamine, 2-methoxyethanamine, tert-butyl acetate,dioxane, trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butylacetate, 1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1a-c schematically represent a device for performing a process forpurifying 2,3,3,3-tetrafluoro-1-propene according to a particularembodiment of the present invention.

FIG. 2 schematically represents a device for performing a process forproducing 2,3,3,3-tetrafluoro-1-propene according to a particularembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The term “hydrocarbon” as used herein refers to linear or branchedC₁-C₂₀ alkane, C₃-C₂₀ cycloalkane, C₂-C₂₀ alkene, C₃-C₂₀ cycloalkene orC₆-C₁₈ arene compounds. For example, the term “alkane” refers tocompounds of formula C_(n)H_(2n+2) in which n is between 1 and 20. Theterm “C₁-C₂₀ alkane” includes, for example, pentane, hexane, heptane,octane, nonane and decane, or isomers thereof. The term “C₂-C₂₀ alkene”refers to hydrocarbon-based compounds comprising one or morecarbon-carbon double bonds and comprising from 2 to 20 carbon atoms Theterm “C₃-C₂₀ cycloalkane” refers to a saturated hydrocarbon-based ringcomprising from 3 to 20 carbon atoms. The term “C₆-C₁₈ aryl” refers tocyclic and aromatic hydrocarbon-based compounds comprising from 6 to 18carbon atoms. The term “C₃-C₂₀ cycloalkene” refers to cyclichydrocarbon-based compounds comprising from 3 to 20 carbon atoms andcomprising one or more carbon-carbon double bonds.

The term “alkyl” denotes a monovalent radical derived from a linear orbranched alkane, comprising from 1 to 20 carbon atoms. The term“cycloalkyl” denotes a monovalent radical derived from a cycloalkane,comprising from 3 to 20 carbon atoms. The term “aryl” denotes amonovalent radical derived from an arene, comprising from 6 to 18 carbonatoms. The term “alkenyl” denotes a monovalent radical of 2 to 20 carbonatoms and at least one carbon-carbon double bond. The term “alkynyl”denotes a monovalent radical of 2 to 20 carbon atoms and at least onecarbon-carbon triple bond. The term “halogen” refers to an —F, —Cl, —Bror —I group. The term “cycloalkenyl” refers to a monovalent radicalderived from a cycloalkene comprising from 3 to 20 carbon atoms. TheC₁-C₂₀ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl, C₃-C₂₀ cycloalkyl, C₃-C₂₀cycloalkenyl and C₆-C₁₈ aryl substituents may be optionally substitutedwith one or more —OH, halogen, —NR^(a)C(O)R^(b), —C(O)NR^(a)R^(b)—CN,—NO₂, —NR^(a)R^(b), —OR, —SR^(a), —CO₂R^(a), —OC(O)OR^(a), —OC(O)R^(a),—C(O)H or —C(O)R^(a) substituents in which R^(a) and R^(b) are,independently of each other, hydrogen, unsubstituted C₁-C₂₀ alkyl,unsubstituted C₂-C₂₀ alkenyl, unsubstituted C₂-C₂₀ alkynyl,unsubstituted C₃-C₂₀ cycloalkyl, unsubstituted C₃-C₂₀ cycloalkenyl orunsubstituted C₆-C₁₈ aryl. In the substituents —NR^(a)R^(b), —NRC(O)R^(b), —C(O)NR^(a)R^(b), R^(a) and R^(b) may form, with the nitrogenatom or with the functional group to which they are attached, asaturated or unsaturated, aromatic or non-aromatic, 4- to 10-memberedheterocycle.

The term “halohydrocarbons” refers to compounds of formula R^(a)X inwhich R^(a) is chosen from C₁-C₂ alkyl, C₂-C₂₀ alkenyl, C₂-C₂₀ alkynyl,C₃-C₂₀ cycloalkyl, C₃-C₂₀ cycloalkenyl and C₆-C₁₈ aryl and X representsa chlorine, fluorine, bromine or iodine atom. The C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₃-C₂ cycloalkyl, C₃-C₂₀ cycloalkenyl andC₆-C₁₈ aryl substituents may be optionally substituted with one or more—OH, halogen, —NR^(a)C(O)R^(b), —C(O)NR^(a)R^(b)—CN, —NO₂, —NR^(a)R^(b),—OR^(a), —SR^(a), —CO₂R^(a), —OC(O)OR^(a), —OC(O)R^(a), —C(O)H or—C(O)R^(a) substituents in which R^(a) and R^(b) are as defined above.

The term “alcohol” refers to hydrocarbons or halohydrocarbons as definedabove in which at least one hydrogen atom is replaced with a hydroxylgroup —OH.

The term “ketone” refers to hydrocarbons comprising at least one or morecarbonyl functional groups R—C(O)—R^(d) in which R^(c) and R^(d) are,independently of each other, a C¹-C²⁰ alkyl, C²-C²⁰ alkenyl, C²-C²⁰alkynyl, C³-C²⁰ cycloalkyl, C³-C²⁰ cycloalkenyl or C⁶-C¹⁸ aryl and maybe optionally substituted with one or more —OH, halogen,—NR^(a)C(O)R^(b), —C(O)NR^(a)R^(b)—CN, —NO₂, —NR^(a)R^(b), —OR^(a),—SR^(a), —CO₂R^(a), —OC(O)OR^(a), —OC(O)R^(a), —C(O)H or —C(O)R^(a)substituents in which R^(a) and R^(b) are as defined above, R^(c) andR^(d) possibly being linked together to form, with the carbonyl group towhich they are attached, a 4- to 10-membered and preferably 4- to7-membered cyclic ketone. The cyclic ketone may also comprise one ormore carbon-carbon double bonds. The cyclic ketone may also beoptionally substituted with one or more substituents as defined above.

The term “amine” refers to hydrocarbons comprising at least one or moreamine functional groups —NR^(c)R^(d) in which R^(c) and R^(d) are asdefined above, R^(c) and R^(d) possibly being linked together to form,with the nitrogen atom to which they are attached, a 4- to 10-memberedaromatic or non-aromatic heterocycle.

The term “esters” refers to compounds of formula R^(c)—C(O)—O—R^(d) inwhich R^(c) and R^(d) are as defined above, R^(c) and R^(d) possiblybeing linked together to form, with the ester group, a ring comprisingfrom 4 to 20 carbon atoms.

The term “ether” refers to compounds of formula R^(c)—O—R^(d) in whichR^(c) and R^(d) are as defined above, R^(c) and R^(d) possibly beinglinked together to form, with the oxygen atom to which they areattached, a heterocycle comprising from 4 to 20 carbon atoms.

The term “aldehyde” refers to compounds comprising at least one or more—C(O)—H functional groups.

The term “nitrile” refers to compounds comprising at least one or more—CN functional groups.

The term “carbonate” refers to compounds of formula R^(c)—O—C(O)—O—R^(d)in which R^(c) and R^(d) are as defined above.

The term “thioalkyl” refers to compounds of formula R^(c)SR^(d) in whichR^(c) and R^(d) are as defined above.

The term “amide” relates to compounds of formula R^(c)C(O)NR^(e)R^(d) inwhich R^(c) and R^(d) are as defined above, R^(e) having the samedefinition as R^(c), R^(c) and R^(d) possibly being linked together toform, with the amide group —C(O)N- to which they are attached, a 4- to10-membered and preferably 4- to 7-membered cyclic amide. The cyclicamide may also comprise one or more carbon-carbon double bonds. Thecyclic amide may also be optionally substituted with one or moresubstituents as defined above.

The term “heterocycle” denotes a 4- to 10-membered carbon-based ring, atleast one of the ring members of which is a heteroatom chosen from thegroup consisting of O, S, P and N. The ring may comprise one or morecarbon-carbon double bonds or one or more carbon-heteroatom double bondsor one or more heteroatoms-heteroatom double bonds. Preferably, theheterocycle may comprise 1, 2, 3, 4 or 5 heteroatoms as defined above.In particular, the heterocycle may comprise 1, 2 or 3 heteroatoms chosenfrom oxygen, nitrogen and sulfur. Preferably, the heterocycle may be a4- to 6-membered carbon-based ring, 1, 2 or 3 ring members of which areheteroatoms chosen from 0 and N. The heterocycle may be optionallysubstituted with one or more substituents chosen from —OH, halogen,—NR^(a)C(O)R^(b), —C(O)NR^(a)R^(b)—CN, —NO₂, —NR^(a)R^(b), —OR^(a),—SR^(a), —CO₂R^(a), —OC(O)OR^(a), —OC(O)R^(a), —C(O)H and —C(O)R^(a) inwhich R^(a) and R^(b) are as defined above.

The term “azeotropic composition” denotes a liquid mixture of two ormore compounds which behave like a single substance, and which boils ata fixed temperature maintaining a composition in the liquid phaseidentical to that in the gas phase. The term “quasi-azeotropiccomposition” denotes a liquid mixture of two or more compounds having aconstant boiling point or which has a tendency not to fractionate whenit is subjected to boiling or to evaporation.

The term “organic extracting agent” refers to a compound comprising atleast one carbon atom.

According to a first aspect, the invention relates to a process forpurifying 2,3,3,3-tetrafluoro-1-propene (1234yf). The purificationprocess is performed using a first composition comprising2,3,3,3-tetrafluoro-1-propene and at least one compound chosen from thegroup consisting of 1,1-difluoroethane (152a), chloropentafluoroethane(115) and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

Preferably, said process comprises the steps of:

-   -   a) placing said first composition in contact with at least one        organic extracting agent to form a second composition;    -   b) extractive distillation of said second composition to form:        -   i) a third composition comprising said organic extracting            agent and at least one of the compounds chosen from the            group consisting of 1,1-difluoroethane (152a),            chloropentafluoroethane (115) and            trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), preferably a            third composition comprising said organic extracting agent            and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and            optionally or not at least one of the compounds chosen from            the group consisting of 1,1-difluoroethane (152a) and            chloropentafluoroethane (115); and        -   ii) a stream comprising 2,3,3,3-tetrafluoro-1-propene;    -   c) recovery and separation of said third composition to form a        stream comprising said organic extracting agent and a stream        comprising said at least one of the compounds chosen from the        group consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); preferably,        recovery and separation of said third composition to form a        stream comprising said organic extracting agent and a stream        comprising trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and        optionally or not at least one of the compounds chosen from the        group consisting of 1,1-difluoroethane (152a) and        chloropentafluoroethane (115).

Preferably, said organic extracting agent is recycled into step a).

Preferably, said stream ii) comprising the 2,3,3,3-tetrafluoropropeneobtained in step b) is recovered.

Said first composition may comprise 2,3,3,3-tetrafluoro-1-propene and atleast two or all of the compounds chosen from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

Preferably, the first composition comprises2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one compound chosen from thegroup consisting of 1,1-difluoroethane (152a) andchloropentafluoroethane (115).

Said first composition may comprise between 75% and 99.99% by weight of2,3,3,3-tetrafluoro-1-propene relative to the total weight of the firstcomposition, advantageously between 80% and 99.9% by weight, preferablybetween 85% and 99.8% and in particular between 90% and 99.5% by weightof 2,3,3,3-tetrafluoro-1-propene relative to the total weight of thefirst composition.

When it contains same, said first composition may comprise less than2000 ppm by weight of 1,1-difluoroethane (152a) relative to the totalweight of the first composition, advantageously between 1 and 1000 ppmby weight, preferably between 1 and 500 ppm and in particular between 1and 250 ppm by weight of 1,1-difluoroethane (152a) relative to the totalweight of the first composition.

When it contains same, said first composition may comprise less than 25%by weight of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) relative tothe total weight of the first composition, advantageously between 0.1%and 20% by weight, preferably between 0.2% and 15%, in particularbetween 0.5% and 10% by weight and more particularly between 3% and 10%by weight of trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) relative tothe total weight of the first composition.

When it contains same, said first composition may comprise less than2000 ppm by weight of chloropentafluoroethane (115) relative to thetotal weight of the first composition, advantageously between 1 and 1000ppm by weight, preferably between 1 and 500 ppm and in particularbetween 1 and 250 ppm by weight of chloropentafluoroethane (115)relative to the total weight of the first composition.

According to a particular embodiment, said organic extracting agent is asolvent chosen from the group consisting of hydrocarbon,halohydrocarbon, alcohol, ketone, amine, ester, ether, aldehyde,nitrile, carbonate, thioalkyl, amide and heterocycle. Alternatively,said organic extracting agent may be difluorodiethylsilane,triethylfluorosilane or perfluorobutanoic acid. Advantageously, saidorganic extracting agent is a solvent chosen from the group consistingof amine, ether, ketone, ester, alcohol, aldehyde and heterocycle.Preferably, the heterocycle may be a 4- to 6-membered carbon-based ring,1, 2 or 3 ring members of which are heteroatoms chosen from O and N.

Preferably, the hydrocarbons are chosen from the group consisting of2,2-dimethylbutane, 3-methylpentane, hexane, 2,4-dimethylpentane,cyclohexane, cyclohexene, methylcyclohexane, 2,4,4-trimethyl-1-pentene,2,2,4-trimethyl-2-pentene, 1-methylcyclohexene, toluene,2,3-dimethylhexane, octane, ethylcyclohexane, ethylbenzene,1,4-dimethylbenzene, 1,2,3-trimethylcyclohexane, 1,2-dimethylbenzene andstyrene.

Preferably, the hydrocarbons are chosen from the group consisting ofchloroethane, 3-chloro-1,1,1,2,2,3-hexafluoropropane,1,1,1,2,2,3,3,4,4-nonafluorobutane,2-chloro-1,1,1,3,3,3-hexafluoropropane, bromofluoromethane,1-bromo-1,2-difluoroethylene, 1-chloro-1,1,2,3,3,3-hexafluoropropane,1-chloro-1,1,2,2-tetrafluoropropane,1-chloro-1,1,2,2,3,3-hexafluoropropane,2-chloro-1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane,trichlorofluoromethane, 1-chloro-1,1-difluoropropane,1,1,1-trifluoro-2-bromoethane, 1,1-dichloro-2,2,2-trifluoroethane,1-chloro-2,2,3,3,3-pentafluoropropane,1,2-dichloro-1,1,2-trifluoroethane, 1,1-dichloroethylene,1,1,1,2,3,4,4,4-octafluorobutane, 2-chloro-2-fluoropropane,1-chloro-2,2-difluoroethane, 2-chloropropane, bromoethane,dichloromethane, 2-chloro-1,1,1,3,3-pentafluoropropane,1-chloro-1,2,2-trifluoropropane, iodomethane,2,2-dichloro-1,1,1,3,3-pentafluoropropane, 3-chloropropene,3-chloro-1,1,1-trifluoropropane, 1,1,1-trichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2-difluoroethane,1,2-dichloro-1,1,2,3,3-pentafluoropropane,1,1,2-trichloro-1,2,2-trifluoroethane,1,2-dichloro-1,1,3,3,3-pentafluoropropane,1-chloro-1,2,2,3-tetrafluoropropane, perfluorocyclohexane,1,1-dichloro-1,2,2,3,3-pentafluoropropane, 2-chloro-2-methylpropane,3-chloro-1,1,1,3-tetrafluoropropane,2,3-dichloro-1,1,1,2,3-pentafluoropropane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane,1,3-dichloro-1,1,2,3,3-pentafluoropropane,1,2-dichloro-3,3,3-trifluoropropene,1,3-dichloro-1,1,2,2,3-pentafluoropropane,1,1,1,2,2,3,4,5,5,5-decafluoropentane,2,2-dichloro-1,1,1,3-tetrafluoropropane, 1-chloro-2,2-difluoropropane,perfluoro-n-hexane, 1,1-dichloroethane, 2-bromopropane,1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane,1,1-dichloro-2,2-difluoroethane,2,2-dichloro-1,1,3,3-tetrafluoropropane, trichloromethane,2,3-dichloro-1,1,1,2-tetrafluoropropane,1,1-dichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,1,2,2-tetrafluoropropane,1,1,1-trichloro-2,2-difluoroethane,1,2-dichloro-1,2,3,3-tetrafluoropropane, chlorobromomethane,2-chlorobutane, 1,3-dichloro-1,1,3,3-tetrafluoropropane,1,3-dichloro-1,2,2,3-tetrafluoropropane,1,2-dichloro-1,1,2,3-tetrafluoropropane, 3-bromopropene,2,3-dichloro-1,1,1,3-tetrafluoropropane, 1,1-dichloro-2-fluoroethane,1-bromopropane, 1,1-difluoro-1,2,2-trichloroethane,1,1,2-trichloro-1,2-difluoroethane, iodoethane, 2-bromo-2-methylpropane,1,2-dichloro-1-fluoroethane, 1,1,1-trichloroethane,1-chloro-3-fluoropropane, 2,3-dichloro-1,1,1-trifluoropropane,perfluoromethylcyclohexane, tetrachloromethane, 1-chlorobutane,perfluoroheptane, 1,3-dichloro-1,1,2-trifluoropropane,1,1-dichloro-2,2,3-trifluoropropane,1,3,3-trichloro-1,1,2,2-tetrafluoropropane, 2-chloro-2-methylbutane,1,1,1-trichloro-2,2,3,3-tetrafluoropropane,1,1,3-trichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,2,2-trifluoropropane, trichloroethene,1,1-dichloropropane, 1,2-dichloro-2-fluoropropane, 2-iodopropane,dichlorobromomethane, 2-bromobutane, 2,2-difluorotetrachloroethane,1,1,2,2-tetrachloro-1,2-difluoroethane, 1-fluorohexane,1,3-dichloro-1,2,3-trifluoropropane, 2,3-dichloro-1-propene,1,2-dichloropropane, 3-chloropentane, trichloroacetaldehyde, isoamylchloride, 1,1,1-trichloro-2,2,3-trifluoropropane,1-chloro-4-fluorobutane, 1-bromo-3-fluoropropane, 1-bromobutane,1,1,2-trichloro-2-fluoroethane, 1-iodopropane,1,1,3-trichloro-1,2,2-trifluoropropane,1,1,3-trichloro-2,2,3-trifluoropropane, cis-1,3-dichloropropene,2,2-dichlorobutane, bromotrichloromethaneperfluorooctane,1,1,1,2-tetrachloro-2-fluoroethane, 1-bromo-2-chloroethane,2-bromo-2-methylbutane, trans-1,3-dichloropropene, 2-fluorotoluene,1,1,1-trichloro-3-fluoropropane, 3,3,3-trichloro-1-propene,1-chloro-3,3-dimethylbutane, 1,1,1,2-tetrachloro-3,3,3-trifluoropropane,2-bromopentane, trichloroacetyl chloride, 2,3-dichlorobutane,1,1,3,3-tetrachloro-1,2,2-trifluoropropane,1,1,1,3-tetrachloro-2,2,3-trifluoropropane, 1-bromo-3-methylbutane,1,3-dichloro-trans-2-butene, 1,3-dichloropropane, tetrachloroethene,1,2-dibromo-1-fluoroethane, 1,2,2-trichloropropane, 1,2-dichlorobutane,perfluorononane, 1,2,2,3-tetrachloro-3,3-difluoropropane,2,3-dichloro-2-methylbutane, 1-bromopentane, 1,2-dichloro-2-butene,1-iodobutane, 1,2-dibromoethane, chlorobenzene, perfluorooctyl bromide,1,1,2-trichloropropane, 1,3-dichlorobutane, pentachlorofluoroethane,1,2-dibromopropane, 1,2,3-trichloropropene, 1-chloro-3-bromopropane,perfluoro-n-decane, 1,1,3,3-tetrachloro-1-fluoropropane,1,1,2,2,3-pentchloro-3,3-difluoropropane, 1,1,2,2-tetrachloroethane,1,2-dichloropentane and tribromomethane.

Preferably, the alcohols are chosen from the group consisting ofmethanol, 2,2,2-trifluoroethanol, 1,1,1-trifluoro-2-propanol, ethanol,pentafluoro-1-propanol, 2-propanol, tert-butanol, 2,2-difluoroethanol,propanol, 2-allyloxyethanol, 2-butanol, 2-methyl-2-butanol, isobutanol,2,2,3,3-tetrafluoro-1-propanol, 2,2-dimethyl-1-propanol, 3-pentanol,1-butanol, 1-methoxy-2-propanol, 1-(dimethylamino)-2-propanol,3-methyl-3-pentanol, 1-chloro-2-methyl-2-propanol,4,4,4-trifluorobutanol, 3-fluoropropanol, 2-chloroethanol,2-methoxyl-propanol, 1-ethoxy-2-propanol, 4-methyl-2-pentanol,1,2-octanediol, 2-chloro-1-propanol, 2-(dimethylamino)ethanol,3-hexanol, 2-hexanol, 2-ethoxy-1-propanol, 1-pentanol,3,3,4,4,5,5,6,6-octafluoro-1-pentanol, 2,3-dimethylbutanol,2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-propoxyethanol,1-propoxy-2-propanol and 2-aminophenol.

Preferably, the ketones are chosen from the group consisting of1,1,1-trifluoro-2-propanone, propanone, butanone, 3-pentanone,2-pentanone, 3,3-dimethyl-2-butanone, 4-methyl-2-pentanone, 2-hexanone,5-hexen-2-one and 4-methyl-2-hexanone.

Preferably, the amines are chosen from the group consisting ofethylamine, isopropylamine, ethylmethylamine, 2-amino-2-methylpropane,n-propylamine, isopropylmethylamine, diethylamine, 2-butanamine,n-methylpropylamine, 1-butylamine, diisopropylamine,3-methyl-2-butanamine, 3-pentylamine, n-methylbutylamine,1-methoxy-2-propanamine, 2-methoxyethanamine, 2-methoxy-1-propanamine,n-pentylamine, n-methylhydroxylamine, dipropylamine, 2-ethoxyethanamine,n-methyl-1,2-ethanediamine, pyridine, 1,2-diaminoethane,1,2-propanediamine, 2-ethylbutylamine, n-ethylethylenediamine,1,1-diethoxy-n,n-dimethylmethanamine, 2-methylpyridine,4-methyl-2-hexanamine, hexylamine, cyclohexylamine,n-ethyl-2-dimethylaminoethylamine, 1,3-propanediamine, 2-heptanamine,n,n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methylpyridine,n,n′-diethyl-1,2-ethanediamine and dimethylethanolamine.

Preferably, the esters are chosen from the group consisting of methylformate, methyl acetate, isopropyl formate, ethyl acetate, n-propylformate, isopropyl acetate, tert-butyl acetate, ethyl propionate,sec-butyl acetate, diethyl carbonate, n-butyl acetate, bromoacetic acidmethyl ester and methyl hexanoate.

Preferably, the ethers are chosen from the group consisting of2,2,2-trifluoroethyl methyl ether, 1,1,2,2-tetrafluoroethyl methylether, 2-methoxy-1-propene, heptafluoro-1-methoxypropane, diethyl ether,ethoxyethene, dimethoxymethane, methyl cyclopropyl ether,2-ethoxypropane, methyl t-butyl ether, ethyl 1,1,2,2-tetrafluoroethylether, chloromethoxymethane, diisopropyl ether,2-ethoxy-2-methylpropane, 2-ethoxybutane, 1-methoxy-2-methylbutane,2,2-dimethoxypropane, 1-ethoxy-2-methylpropane, 1,2-dimethoxyethane,diethoxymethane, di-n-propyl ether, 1-ethoxybutane, 1-methoxypentane,1,2-dimethoxypropane, isopropyl isobutyl ether, 1,1-diethoxyethane,trimethoxymethane, 1,1-dichloro-2,2-difluoroethyl methyl ether,2,2-diethoxypropane, isobutyl tert-butyl ether, sec-butyl tert-butylether, 1,1-diethoxypropane, 2-methoxyethanol,2-chloro-1,1-dimethoxyethane, methoxycyclohexane, ethoxyethanol,di-n-butyl ether, 1-ethoxyhexane, 1-methoxy-2-acetoxypropane and1,1,1-triethoxyethane.

Preferably, the aldehydes are chosen from the group consisting ofacetaldehyde, ethanedial, isobutanal, methylglyoxal, 2-methylbutanal,2,6-dimethyl-5-heptenal and hexanal.

Preferably, the nitriles are chosen from the group consisting ofacetonitrile, propionitrile, butyronitrile, valeronitrile and(methyleneamino)acetonitrile.

Preferably, the carbonate is diethyl carbonate.

Preferably, the amide is ethanethioamide.

Preferably, the thioalkyls are chosen from the group consisting ofethanethiol, dimethyl sulfide, 2-propanethiol,4-methoxy-2-methyl-2-butanethiol, tert-butylthiol, 1-propanethiol,thiophene, 2-butanethiol, 2-methyl-1-propanethiol, diethyl sulfide,butanethiol, 3-mercapto-1,2-propanediol, tetrahydrothiophene and1-pentanethiol.

Preferably, the heterocycles are chosen from the group consisting offuran, 1,2-epoxypropane, tetrahydrofuran, dioxane, 1,3-dioxane,piperidine, 1,3,5-trioxane, n-methylmorpholine, 2-methylpyrazine,1-methylpiperazine, n-ethylmorpholine, 2,6-dimethylmorpholine and3-furfural.

Said organic extracting agent may be chloroethane,3-chloro-1,1,1,2,2,3-hexafluoropropane,1,1,1,2,2,3,3,4,4-nonafluorobutane,2-chloro-1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-pentafluoropropane,ethylamine, bromofluoromethane, 1-bromo-1,2-difluoroethylene,1-chloro-1,1,2,3,3,3-hexafluoropropane,1-chloro-1,1,2,2-tetrafluoropropane, acetaldehyde,1-chloro-1,1,2,2,3,3-hexafluoropropane, 1,1,1-trifluoro-2-propanone,2-chloro-1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane,trichlorofluoromethane, 1-chloro-1,1-difluoropropane,1,1,1-trifluoro-2-bromoethane, 1,1-dichloro-2,2,2-trifluoroethane,1-chloro-2,2,3,3,3-pentafluoropropane,1,2-dichloro-1,1,2-trifluoroethane, 2,2,2-trifluoroethyl methyl ether,1,1-dichloroethylene, furan, methyl formate, isopropylamine,1,1,2,2-tetrafluoroethyl methyl ether, 1,1,1,2,3,4,4,4-octafluorobutane,2-methoxy-1-propene, heptafluoro-1-methoxypropane, diethyl ether,1,2-epoxypropane, ethanethiol, 2-chloro-2-fluoropropane, ethoxyethene,1-chloro-2,2-difluoroethane, ethylmethylamine, dimethyl sulfide,2-chloropropane, bromoethane, dichloromethane, dimethoxymethane,2-chloro-1,1,1,3,3-pentafluoropropane, 1-chloro-1,2,2-trifluoropropane,iodomethane, 2,2-dichloro-1,1,1,3,3-pentafluoropropane,2-amino-2-methylpropane, methyl cyclopropyl ether, 3-chloropropene,3-chloro-1,1,1-trifluoropropane, 1,1,1-trichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2-difluoroethane,1,2-dichloro-1,1,2,3,3-pentafluoropropane, n-propylamine,1,1,2-trichloro-1,2,2-trifluoroethane, 2,2, dimethylbutane,isopropylmethylamine, ethanedial,1,2-dichloro-1,1,3,3,3-pentafluoropropane,1-chloro-1,2,2,3-tetrafluoropropane, perfluorocyclohexane,1,1-dichloro-1,2,2,3,3-pentafluoropropane, 2-chloro-2-methylpropane,3-chloro-1,1,1,3-tetrafluoropropane,2,3-dichloro-1,1,1,2,3-pentafluoropropane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-propanethiol,1,3-dichloro-1,1,2,3,3-pentafluoropropane,1,2-dichloro-3,3,3-trifluoropropene,1,3-dichloro-1,1,2,2,3-pentafluoropropane,1,1,1,2,2,3,4,5,5,5-decafluoropentane, 2-ethoxypropane,2,2-dichloro-1,1,1,3-tetrafluoropropane, 1-chloro-2,2-difluoropropane,methyl t-butyl ether, diethylamine, propanone, perfluoro-n-hexane,methyl acetate, 1,1-dichloroethane, ethyl 1,1,2,2-tetrafluoroethylether, 4-methoxy-2-methyl-2-butanethiol, 2-bromopropane,chloromethoxymethane, 1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane,1,1-dichloro-2,2-difluoroethane,2,2-dichloro-1,1,3,3-tetrafluoropropane, difluorodiethylsilane,2-butanamine, 2,3-dichloro-1,1,1,2-tetrafluoropropane,n-methylpropylamine, 3-methylpentane,1,1-dichloro-1,2,2,3-tetrafluoropropane, tert-butylthiol, isobutanal,methanol, tetrahydrofuran, 1,3-dichloro-1,1,2,2-tetrafluoropropane,1,1,1-trichloro-2,2-difluoroethane,1,2-dichloro-1,2,3,3-tetrafluoropropane, 1-propanethiol,chlorobromomethane, 2-chlorobutane, isopropyl formate, diisopropylether, 1,3-dichloro-1,1,3,3-tetrafluoropropane, hexane,1,3-dichloro-1,2,2,3-tetrafluoropropane,1,2-dichloro-1,1,2,3-tetrafluoropropane, 3-bromopropene,2,3-dichloro-1,1,1,3-tetrafluoropropane, 1,1-dichloro-2-fluoroethane,1-bromopropane, 1,1-difluoro-1,2,2-trichloroethane,1,1,2-trichloro-1,2-difluoroethane, methylglyoxal, iodoethane,2-ethoxy-2-methylpropane, 2-bromo-2-methylpropane,1,2-dichloro-1-fluoroethane, 1,1,1-trichloroethane,2,2,2-trifluoroethanol, 1-chloro-3-fluoropropane,1,1,1-trifluoro-2-propanol, 2,3-dichloro-1,1,1-trifluoropropane,perfluoromethylcyclohexane, ethyl acetate, 1-butylamine, 1-chlorobutane,ethanol, butanone, 2,4-dimethylpentane, cyclohexane, n-propyl formate,2-ethoxybutane, acetonitrile, pentafluoro-1-propanol, 2-propanol,tert-butanol, perfluoroheptane, 1,3-dichloro-1,1,2-trifluoropropane,1-methoxy-2-methylbutane, 1,1-dichloro-2,2,3-trifluoropropane,cyclohexene, 2,2-dimethoxypropane,1,3,3-trichloro-1,1,2,2-tetrafluoropropane, 2-chloro-2-methylbutane,1,2-dichloroethane, 1-ethoxy-2-methylpropane, diisopropylamine,thiophene, 2-butanethiol, 1,1,1-trichloro-2,2,3,3-tetrafluoropropane,1,2-dimethoxyethane, 3-methyl-2-butanamine,1,1,3-trichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,2,2-trifluoropropane, diethoxymethane,1,1-dichloropropane, 2-methyl-1-propanethiol,1,2-dichloro-2-fluoropropane, isopropyl acetate, 2-iodopropane,di-n-propyl ether, 3-pentylamine, n-methylbutylamine, 2-bromobutane,2,2-difluorotetrachloroethane, diethyl sulfide, 1-ethoxybutane,1,1,2,2-tetrachloro-1,2-difluoroethane, 1-fluorohexane,1-methoxy-2-propanamine, 1,3-dichloro-1,2,3-trifluoropropane,2,3-dichloro-1-propene, 2-methoxyethanamine, 2,2-difluoroethanol,2-methylbutanal, 1,2-dichloropropane, propanol, tert-butyl acetate,propionitrile, 3-chloropentane, trichloroacetaldehyde,2-allyloxyethanol, butanethiol, isoamyl chloride, 1-methoxypentane,ethyl propionate, 2-butanol, 1,2-dimethoxypropane, isopropyl isobutylether, 1,1,1-trichloro-2,2,3-trifluoropropane, methylcyclohexane,1-chloro-4-fluorobutane, 1-bromo-3-fluoropropane,2,4,4-trimethyl-1-pentene, dioxane, 1-bromobutane, 3-pentanone,1,1,2-trichloro-2-fluoroethane, 1,1-diethoxyethane, 2-pentanone,2-methyl-2-butanol, 1-iodopropane, 2-methoxy-1-propanamine,1,1,3-trichloro-1,2,2-trifluoropropane,1,1,3-trichloro-2,2,3-trifluoropropane, trimethoxymethane,cis-1,3-dichloropropene, 2,2-dichlorobutane, n-pentylamine,1,1-dichloro-2,2-difluoroethyl methyl ether, 2,2,4-trimethyl-2-pentene,perfluorooctane, 1,1,1,2-tetrachloro-2-fluoroethane, 1,3-dioxane,3,3-dimethyl-2-butanone, piperidine, 1-bromo-2-chloroethane, isobutanol,2-bromo-2-methylbutane, dipropylamine, 2,2,3,3-tetraflouro-1-propanol,2-ethoxyethanamine, triethylfluorosilane, 1-methylcyclohexene, toluene,trans-1,3-dichloropropene, sec-butyl acetate, 2-fluorotoluene,2,2-dimethyl-1-propanol, 1,1,1-trichloro-3-fluoropropane,n-methyl-1,2-ethanediamine, 2,2-diethoxypropane, 1,3,5-trioxane,3,3,3-trichloro-1-propene, 1-chloro-3,3-dimethylbutane, pyridine,2,3-dimethylhexane, 1,1,1,2-tetrachloro-3,3,3-trifluoropropane,n-methylmorpholine, 3-pentanol, 4-methyl-2-pentanone, 1,2-diaminoethane,isobutyl tert-butyl ether, 2-bromopentane, butyronitrile, 1-butanol,2,3-dichlorobutane, sec-butyl tert-butyl ether, 1-methoxy-2-propanol,1,1,3,3-tetrachloro-1,2,2-trifluoropropane, 1,2-propanediamine,2,6-dimethyl-5-heptenal, perfluorobutanoic acid,1,1,1,3-tetrachloro-2,2,3-trifluoropropane, 1-bromo-3-methylbutane,1,3-dichloro-trans-2-butene, 1,3-dichloropropane,1-(dimethylamino)-2-propanol, tetrahydrothiophene, 3-methyl-3-pentanol,1,2-dibromo-1-fluoroethane, 1,1-diethoxypropane, 1,2,2-trichloropropane,1-chloro-2-methyl-2-propanol, 2-methoxyethanol, 1,2-dichlorobutane,4,4,4-trifluorobutanol, 2-ethylbutylamine, perfluorononane, octane,diethyl carbonate, n-butyl acetate, 1-pentanethiol,1,2,2,3-tetrachloro-3,3-difluoropropane, 2-chloro-1,1-dimethoxyethane,2-hexanone, n-ethylethylenediamine, 3-fluoropropanol, 5-hexen-2-one,2,3-dichloro-2-methylbutane, 1,1-diethoxy-n,n-dimethylmethanamine,2-methylpyridine, 1-bromopentane, 2-methoxy-1-propanol,1,2-dichloro-2-butene, 1-iodobutane, 1-ethoxy-2-propanol, hexanal,4-methyl-2-pentanol, 1,2-dibromoethane, chlorobenzene, ethylcyclohexane,perfluorooctyl bromide, bromoacetic acid methyl ester,1,1,2-trichloropropane, 1,2-octanediol, 4-methyl-2-hexanamine,hexylamine, 2-chloro-1-propanol, 2-(dimethylamino)ethanol,1,3-dichlorobutane, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine,ethoxyethanol, 3-hexanol, 2-hexanol, ethylbenzene, 2-methylpyrazine,2-ethoxy-1-propanol, 1-pentanol, 1-methylpiperazine, n-ethylmorpholine,1,4-dimethylbenzene, 1,3-dimethylbenzene, 1,3-propanediamine, di-n-butylether, 3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile,(methyleneamino)acetonitrile, 1,2-dibromopropane, 2-heptanamine,1,2,3-trichloropropene, 1,2,3-trimethylcyclohexane, 2,3-dimethylbutanol,1-ethoxyhexane, 1-chloro-3-bromopropane, perfluoro-n-decane, 3-furfural,n,n-diethylethylenediamine, 2,6-dimethylpyridine,1,1,3,3-tetrachloro-1-fluoropropane, 4-methyl-2-hexanone,1,2-dimethylbenzene, 1,1,2,2,3-pentchloro-3,3-difluoropropane,1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane, styrene,4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, 2-ethyl-1-butanol, 1,2-dichloropentane,2-methyl-1-pentanol, methyl hexanoate, 2-propoxyethanol,dimethylethanolamine or 1-propoxy-2-propanol.

Advantageously, said organic extracting agent may be chloroethane,3-chloro-1,1,1,2,2,3-hexafluoropropane,1,1,1,2,2,3,3,4,4-nonafluorobutane,2-chloro-1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-pentafluoropropane,ethylamine, bromofluoromethane, 1-bromo-1,2-difluoroethylene,1-chloro-1,1,2,3,3,3-hexafluoropropane,1-chloro-1,1,2,2-tetrafluoropropane, acetaldehyde,1-chloro-1,1,2,2,3,3-hexafluoropropane, 1,1,1-trifluoro-2-propanone,2-chloro-1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane,1-chloro-1,1-difluoropropane, 1,1,1-trifluoro-2-bromoethane,1,1-dichloro-2,2,2-trifluoroethane,1-chloro-2,2,3,3,3-pentafluoropropane,1,2-dichloro-1,1,2-trifluoroethane, 2,2,2-trifluoroethyl methyl ether,furan, methyl formate, isopropylamine, 1,1,2,2-tetrafluoroethyl methylether, 1,1,1,2,3,4,4,4-octafluorobutane, 2-methoxy-1-propene,heptafluoro-1l-methoxypropane, diethyl ether, 1,2-epoxypropane,ethanethiol, 2-chloro-2-fluoropropane, ethoxyethene,1-chloro-2,2-difluoroethane, ethylmethylamine, dimethyl sulfide,2-chloropropane, bromoethane, dimethoxymethane,2-chloro-1,1,1,3,3-pentafluoropropane, 1-chloro-1,2,2-trifluoropropane,2,2-dichloro-1,1,1,3,3-pentafluoropropane, 2-amino-2-methylpropane,methyl cyclopropyl ether, 3-chloropropene,3-chloro-1,1,1-trifluoropropane, 1,1,1-trichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2-difluoroethane,1,2-dichloro-1,1,2,3,3-pentafluoropropane, n-propylamine,1,1,2-trichloro-1,2,2-trifluoroethane, isopropylmethylamine, ethanedial,1,2-dichloro-1,1,3,3,3-pentafluoropropane,1-chloro-1,2,2,3-tetrafluoropropane, perfluorocyclohexane,1,1-dichloro-1,2,2,3,3-pentafluoropropane, 2-chloro-2-methylpropane,3-chloro-1,1,1,3-tetrafluoropropane,2,3-dichloro-1,1,1,2,3-pentafluoropropane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-propanethiol,1,2-dichloro-3,3,3-trifluoropropene,1,1,1,2,2,3,4,5,5,5-decafluoropentane, 2-ethoxypropane,2,2-dichloro-1,1,1,3-tetrafluoropropane, 1-chloro-2,2-difluoropropane,methyl t-butyl ether, diethylamine, propanone, perfluoro-n-hexane,methyl acetate, ethyl 1,1,2,2-tetrafluoroethyl ether,4-methoxy-2-methyl-2-butanethiol, 2-bromopropane,1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane,1,1-dichloro-2,2-difluoroethane,2,2-dichloro-1,1,3,3-tetrafluoropropane, difluorodiethylsilane,2-butanamine, 2,3-dichloro-1,1,1,2-tetrafluoropropane,n-methylpropylamine, 1,1-dichloro-1,2,2,3-tetrafluoropropane,tert-butylthiol, isobutanal, tetrahydrofuran,1,3-dichloro-1,1,2,2-tetrafluoropropane,1,1,1-trichloro-2,2-difluoroethane,1,2-dichloro-1,2,3,3-tetrafluoropropane, 1-propanethiol, 2-chlorobutane,isopropyl formate, diisopropyl ether,1,3-dichloro-1,2,2,3-tetrafluoropropane,1,2-dichloro-1,1,2,3-tetrafluoropropane,2,3-dichloro-1,1,1,3-tetrafluoropropane, 1-bromopropane,1,1-difluoro-1,2,2-trichloroethane, 1,1,2-trichloro-1,2-difluoroethane,methylglyoxal, 2-ethoxy-2-methylpropane, 2-bromo-2-methylpropane,1-chloro-3-fluoropropane, 1,1,1-trifluoro-2-propanol,2,3-dichloro-1,1,1-trifluoropropane, perfluoromethylcyclohexane, ethylacetate, 1-butylamine, 1-chlorobutane, butanone, n-propyl formate,2-ethoxybutane, pentafluoro-1-propanol, 2-propanol, tert-butanol,perfluoroheptane, 1,3-dichloro-1,1,2-trifluoropropane,1-methoxy-2-methylbutane, 1,1-dichloro-2,2,3-trifluoropropane,cyclohexene, 2,2-dimethoxypropane,1,3,3-trichloro-1,1,2,2-tetrafluoropropane, 2-chloro-2-methylbutane,1-ethoxy-2-methylpropane, diisopropylamine, 2-butanethiol,1,1,1-trichloro-2,2,3,3-tetrafluoropropane, 1,2-dimethoxyethane,3-methyl-2-butanamine, 1,1,3-trichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,2,2-trifluoropropane, diethoxymethane,2-methyl-1-propanethiol, isopropyl acetate, 2-iodopropane, di-n-propylether, 3-pentylamine, n-methylbutylamine, 2-bromobutane, diethylsulfide, 1-ethoxybutane, 1-fluorohexane, 1-methoxy-2-propanamine,1,3-dichloro-1,2,3-trifluoropropane, 2-methoxyethanamine,2-methylbutanal, propanol, tert-butyl acetate, propionitrile,3-chloropentane, 2-allyloxyethanol, butanethiol, isoamyl chloride,1-methoxypentane, ethyl propionate, 2-butanol, 1,2-dimethoxypropane,isopropyl isobutyl ether, 1,1,1-trichloro-2,2,3-trifluoropropane,1-chloro-4-fluorobutane, 1-bromo-3-fluoropropane,2,4,4-trimethyl-1-pentene, dioxane, 1-bromobutane, 3-pentanone,1,1-diethoxyethane, 2-pentanone, 2-methyl-2-butanol,2-methoxy-1-propanamine, 1,1,3-trichloro-1,2,2-trifluoropropane,1,1,3-trichloro-2,2,3-trifluoropropane, trimethoxymethane,n-pentylamine, 1,1-dichloro-2,2-difluoroethyl methyl ether,2,2,4-trimethyl-2-pentene, perfluorooctane, 1,3-dioxane,3,3-dimethyl-2-butanone, piperidine, isobutanol, 2-bromo-2-methylbutane,dipropylamine, 2,2,3,3-tetraflouro-1-propanol, 2-ethoxyethanamine,triethylfluorosilane, 1-methylcyclohexene, toluene, sec-butyl acetate,2-fluorotoluene, 2,2-dimethyl-1-propanol, n-methyl-1,2-ethanediamine,2,2-diethoxypropane, 1,3,5-trioxane, 1-chloro-3,3-dimethylbutane,pyridine, 1,1,1,2-tetrachloro-3,3,3-trifluoropropane,n-methylmorpholine, 3-pentanol, 4-methyl-2-pentanone, 1,2-diaminoethane,isobutyl tert-butyl ether, 2-bromopentane, butyronitrile, 1-butanol,sec-butyl tert-butyl ether, 1-methoxy-2-propanol,1,1,3,3-tetrachloro-1,2,2-trifluoropropane, 1,2-propanediamine,2,6-dimethyl-5-heptenal, perfluorobutanoic acid,1,1,1,3-tetrachloro-2,2,3-trifluoropropane, 1-bromo-3-methylbutane,1-(dimethylamino)-2-propanol, tetrahydrothiophene, 3-methyl-3-pentanol,1,1-diethoxypropane, 2-methoxyethanol, 4,4,4-trifluorobutanol,2-ethylbutylamine, perfluorononane, diethyl carbonate, n-butyl acetate,1-pentanethiol, 2-chloro-1,1-dimethoxyethane, 2-hexanone,n-ethylethylenediamine, 5-hexen-2-one,1,1-diethoxy-n,n-dimethylmethanamine, 2-methylpyridine, 1-bromopentane,2-methoxy-1-propanol, 1-ethoxy-2-propanol, hexanal, 4-methyl-2-pentanol,perfluorooctyl bromide, 1,2-octanediol, 4-methyl-2-hexanamine,hexylamine, methoxycyclohexane, 2-(dimethylamino)ethanol,cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, ethoxyethanol,3-hexanol, 2-hexanol, ethylbenzene, 2-methylpyrazine,2-ethoxy-1-propanol, 1-pentanol, 1-methylpiperazine, n-ethylmorpholine,1,4-dimethylbenzene, 1,3-dimethylbenzene, 1,3-propanediamine, di-n-butylether, 3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile,(methyleneamino)acetonitrile, 2-heptanamine, 2,3, dimethylbutanol,1-ethoxyhexane, perfluoro-n-decane, 3-furfural,n,n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methyl-2-hexanone,1,2-dimethylbenzene, 1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane,styrene, 4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, 2-ethyl-1-butanol, 2-methyl-1-pentanol, methylhexanoate, 2-propoxyethanol, dimethylethanolamine or1-propoxy-2-propanol.

Preferably, said organic extracting agent may be ethylamine,acetaldehyde, 1,1,1,3,3-pentafluoropropane, 1,1,1-trifluoro-2-propanone,1,1,1,2,3-pentafluoropropane, 2,2,2-trifluoroethyl methyl ether, methylformate, isopropylamine, 1,1,2,2-tetrafluoroethyl methyl ether,2-methoxy-1-propene, diethyl ether, 1,2-epoxypropane, ethoxyethene,ethylmethylamine, dimethoxymethane, 1-chloro-1,2,2-trifluoropropane,2-amino-2-methylpropane, methyl cyclopropyl ether,3-chloro-1,1,1-trifluoropropane, n-propylamine, isopropylmethylamine,ethanedial, 1-chloro-1,2,2,3-tetrafluoropropane,3-chloro-1,1,1,3-tetrafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-ethoxypropane, methyl t-butylether, diethylamine, propanone, methyl acetate, ethyl1,1,2,2-tetrafluoroethyl ether, 4-methoxy-2-methyl-2-butanethiol,difluorodiethylsilane, 2-butanamine, n-methylpropylamine, isobutanal,tetrahydrofuran, 1,3-dichloro-1,1,2,2-tetrafluoropropane, isopropylformate, diisopropyl ether, methylglyoxal, 2-ethoxy-2-methylpropane,2,3-dichloro-1,1,1-trifluoropropane, ethyl acetate, 1-butylamine,butanone, n-propyl formate, 2-ethoxybutane,1,3-dichloro-1,1,2-trifluoropropane, 1-methoxy-2-methylbutane,1,1-dichloro-2,2,3-trifluoropropane, 2,2-dimethoxypropane,1-ethoxy-2-methylpropane, diisopropylamine, 1,2-dimethoxyethane,3-methyl-2-butanamine, 1,3-dichloro-1,2,2-trifluoropropane,diethoxymethane, isopropyl acetate, di-n-propyl ether, 3-pentylamine,n-methylbutylamine, diethyl sulfide, 1-ethoxybutane, 1-fluorohexane,1-methoxy-2-propanamine, 1,3-dichloro-1,2,3-trifluoropropane,2-methoxyethanamine, 2-methylbutanal, tert-butyl acetate, propionitrile,2-allyloxyethanol, 1-methoxypentane, ethyl propionate,1,2-dimethoxypropane, isopropyl isobutyl ether, dioxane, 3-pentanone,1,1-diethoxyethane, 2-pentanone, 2-methoxy-1-propanamine,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,piperidine, dipropylamine, 2-ethoxyethanamine, triethylfluorosilane,sec-butyl acetate, n-methyl-1,2-ethanediamine, 2,2-diethoxypropane,pyridine, n-methylmorpholine, 4-methyl-2-pentanone, 1,2-diaminoethane,isobutyl tert-butyl ether, butyronitrile, sec-butyl tert-butyl ether,1-methoxy-2-propanol, 1,2-propanediamine, 2,6-dimethyl-5-heptenal,perfluorobutanoic acid, 1-(dimethylamino)-2-propanol,3-methyl-3-pentanol, 1,1-diethoxypropane, 2-ethylbutylamine, diethylcarbonate, n-butyl acetate, 2-hexanone, n-ethylethylenediamine,5-hexen-2-one, 1,1-diethoxy-n,n-dimethylmethanamine, 2-methylpyridine,2-methoxy-1-propanol, 1-ethoxy-2-propanol, hexanal,4-methyl-2-hexanamine, hexylamine, methoxycyclohexane,2-(dimethylamino)ethanol, cyclohexylamine,n-ethyl-2-dimethylaminoethylamine, ethoxyethanol, 2-methylpyrazine,2-ethoxy-1-propanol, 1-methylpiperazine, n-ethylmorpholine,1,3-propanediamine, di-n-butyl ether,3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile, 2-heptanamine,1-ethoxyhexane, n,n-diethylethylenediamine, 2,6-dimethylpyridine,4-methyl-2-hexanone, 1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane,4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, methyl hexanoate, 2-propoxyethanol or1-propoxy-2-propanol.

In particular, said organic extracting agent may be ethylamine,1,1,1-trifluoro-2-propanone, methyl formate, isopropylamine,2-methoxy-1-propene, diethyl ether, 1,2-epoxypropane, ethoxyethene,ethylmethylamine, dimethoxymethane, 2-amino-2-methylpropane, methylcyclopropyl ether, n-propylamine, isopropylmethylamine, 2-ethoxypropane,methyl t-butyl ether, diethylamine, propanone, methyl acetate,2-butanamine, n-methylpropylamine, isobutanal, tetrahydrofuran,isopropyl formate, diisopropyl ether, 2-ethoxy-2-methylpropane, ethylacetate, 1-butylamine, butanone, n-propyl formate, 2-ethoxybutane,1-methoxy-2-methylbutane, 2,2-dimethoxypropane,1-ethoxy-2-methylpropane, 1,2-dimethoxyethane, 3-methyl-2-butanamine,diethoxymethane, isopropyl acetate, di-n-propyl ether, 3-pentylamine, n,methylbutylamine, 1-ethoxybutane, 1-methoxy-2-propanamine,2-methoxyethanamine, 2-methylbutanal, tert-butyl acetate,1-methoxypentane, ethyl propionate, 1,2-dimethoxypropane, dioxane,3-pentanone, 1,1-diethoxyethane, 2-pentanone, 2-methoxy-1-propanamine,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,piperidine, 2-ethoxyethanamine, sec-butyl acetate,n-methyl-1,2-ethanediamine, 2,2-diethoxypropane, 4-methyl-2-pentanone,1,2-diaminoethane, butyronitrile, 1-methoxy 2-propanol,1,2-propanediamine, 2,6-dimethyl-5-heptenal,1-(dimethylamino)-2-propanol, 1,1-diethoxypropane, 2-ethylbutylamine,diethyl carbonate, n-butyl acetate, 2-hexanone, n-ethylethylenediamine,5-hexen-2-one, 2-methylpyridine, 2-methoxy-1-propanol,1-ethoxy-2-propanol, hexanal, 4-methyl-2-hexanamine, hexylamine,methoxycyclohexane, 2-(dimethylamino)ethanol, cyclohexylamine,n-ethyl-2-dimethylaminoethylamine, 2-methylpyrazine,2-ethoxy-1-propanol, 1-methylpiperazine, 1,3-propanediamine, di-n-butylether, valeronitrile, 2-heptanamine, 1-ethoxyhexane,n,n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methyl-2-hexanone,1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane, 4-methylpyridine,n,n′-diethyl-1,2-ethanediamine, 2,6-dimethylmorpholine, methylhexanoate, 2-propoxyethanol or 1-propoxy-2-propanol.

More particularly, said organic extracting agent may be ethylamine,isopropylamine, diethyl ether, ethoxyethene, dimethoxymethane,n-propylamine, methyl t-butyl ether, diethylamine, propanone, methylacetate, isobutanal, tetrahydrofuran, isopropyl formate, diisopropylether, 2-ethoxy-2-methylpropane, ethyl acetate, butanone,diethoxymethane, isopropyl acetate, 3-pentylamine, 2-methoxyethanamine,tert-butyl acetate, dioxane, 3-pentanone, 1,1-diethoxyethane,2-pentanone, trimethoxymethane, n-pentylamine, 1,3-dioxane,3,3-dimethyl-2-butanone, sec-butyl acetate, 4-methyl-2-pentanone,1,2-diaminoethane, 1-methoxy-2-propanol, diethyl carbonate, n-butylacetate, 1-ethoxy-2-propanol or hexanal.

Preferentially, said organic extracting agent may be chosen fromethylamine, isopropylamine, diethyl ether, dimethoxymethane,n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, butanone, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal. More preferentially, said organicextracting agent may be chosen from ethylamine, isopropylamine, diethylether, dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal.

The organic extracting agent to be used may be chosen as a function ofthe compounds present in said first composition. Thus, the organicextracting agent may be chosen as a function of the separation factorand of the absorption capacity established for a particular composition.Besides these two criteria, the choice of the organic extracting agentmay be optionally based on other commercial or environmental criteria,for instance the cost of the organic extracting agent, its availabilityon the market, and its toxicity or flammability properties. Furthermore,according to a particular embodiment, in order to optimize thefunctioning of the distillation columns used in the steps b) and c) ofthe present process for purifying 2,3,3,3-tetrafluoro-1-propene, theboiling point of the organic extracting agent may be from 10° C. to 200°C., advantageously from 10′C to 190° C., preferably from 10′C to 180°C., in particular from 10′C to 170° C., preferentially from 10′C to160′C and more preferentially from 10° C. to 150° C.

According to a preferred embodiment, said organic extracting agent has aseparation factor S_(1,2) of greater than or equal to 1.1, saidseparation factor being calculated by the formulaS_(1,2)=(γ_(1,S)*P1)/(γ_(2,S)*P2) in which

-   -   γ_(1,S) represents the activity coefficient of        2,3,3,3-tetrafluoro-1-propene in said organic extracting agent        at infinite dilution;    -   P1 represents the saturating vapor pressure of        2,3,3,3-tetrafluoro-1-propene;    -   γ_(2,S) represents the activity coefficient of said at least one        compound consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organic        extracting agent at infinite dilution, advantageously the        activity coefficient of trans-1,3,3,3-tetrafluoro-1-propene        (1234ze-E);    -   P2 represents the saturating vapor pressure of said at least one        compound consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), advantageously        the saturating vapor pressure of        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).

Advantageously, the separation factor S_(1,2) is greater than or equalto 1.2, preferably greater than or equal to 1.4, more preferentiallygreater than or equal to 1.6, in particular greater than or equal to1.8, more particularly greater than or equal to 2.0.

According to a preferred embodiment, said organic extracting agent hasan absorption capacity C_(2,S) of greater than or equal to 0.20, saidabsorption capacity being calculated by the formula C_(2,S)=1/(γ_(2,S))in which γ_(2,S) represents the activity coefficient of said at leastone compound consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) in said organic extracting agent at infinite dilution;advantageously, the activity coefficient of1,3,3,3-tetrafluoro-1-propene (1234ze-E).

Advantageously, the absorption capacity C_(2,S) is greater than or equalto 0.40, preferably greater than or equal to 0.60, more preferentiallygreater than or equal to 0.80, in particular greater than or equal to1.0.

According to a preferred embodiment, said organic extracting agent mayhave a separation factor S_(1,2) of greater than or equal to 1.1,advantageously greater than or equal to 1.2, preferably greater than orequal to 1.4, more preferentially greater than or equal to 1.6, inparticular greater than or equal to 1.8 and more particularly greaterthan or equal to 2.0; and an absorption capacity C_(2,S) of greater thanor equal to 0.20, advantageously greater than or equal to 0.40,preferably greater than or equal to 0.60, more preferentially greaterthan or equal to 0.80 and in particular greater than or equal to 1.0.

Said first composition may be an azeotropic or quasi-azeotropiccomposition comprising 2,3,3,3-tetrafluoro-1-propene and said at leastone compound chosen from the group consisting of 1,1-difluoroethane(152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E). Advantageously, saidfirst composition may be an azeotropic or quasi-azeotropic compositioncomprising 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or not atleast one compound chosen from the group consisting of1,1-difluoroethane (152a) and chloropentafluoroethane (115).

Said first composition may be an azeotropic or quasi-azeotropiccomposition comprising 2,3,3,3-tetrafluoro-1-propene and at least two orall of the compounds chosen from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E). Advantageously, saidfirst composition may be an azeotropic or quasi-azeotropic compositioncomprising 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and at least one or bothcompounds chosen from the group consisting of 1,1-difluoroethane (152a)and chloropentafluoroethane (115).

Depending on the compound(s) to be removed in said first composition,said separation factor and said absorption capacity may be calculatedfor a particular binary couple consisting of2,3,3,3-tetrafluoro-1-propene and one of the compounds chosen from thegroup consisting of 1,1-difluoroethane (152a), chloropentafluoroethane(115) and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E). Thus, toselect said organic extracting agent that is suitable for use in theextractive distillation step b), the separation factor and theabsorption capacity may be calculated, for example, for a2,3,3,3-tetrafluoro-1-propene and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) binary couple if said first composition comprises these twocompounds. The separation factor S_(1,2) makes it possible to determinethe capacity of an organic extracting agent to separate two or morecompounds. The absorption capacity C_(2,S) makes it possible todetermine the amount of solvent to be used to obtain separation betweenthe compounds under consideration. For all of the first compositionsdetailed below, said organic extracting agent may have a separationfactor S_(1,2) of greater than or equal to 1.1, advantageously greaterthan or equal to 1.2, preferably greater than or equal to 1.4, morepreferentially greater than or equal to 1.6, in particular greater thanor equal to 1.8 and more particularly greater than or equal to 2.0;and/or said organic extracting agent may have an absorption capacityC_(2,S) of greater than or equal to 0.20, advantageously greater than orequal to 0.40, preferably greater than or equal to 0.60, morepreferentially greater than or equal to 0.80 and in particular greaterthan or equal to 1.0.

In particular, said first composition may be an azeotropic orquasi-azeotropic composition comprising 2,3,3,3-tetrafluoro-1-propeneand trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E). The content of eachof the compounds in this particular composition is as expressed abovewith reference to the individual contents of each of the compounds.Thus, the second composition may comprise 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and said organicextracting agent. Said organic extracting agent may have a separationfactor S_(1,2) of greater than or equal to 1.1, said separation factorbeing calculated by the formula S_(1,2)=(γ_(1,S)*P1)/(γ_(2,S)*P2) inwhich γ_(1,S) represents the activity coefficient of2,3,3,3-tetrafluoro-1-propene relative to said organic extracting agent,P1 represents the saturating vapor pressure of2,3,3,3-tetrafluoro-1-propene, γ_(2,S) represents the activitycoefficient of trans-1,3,3,3-tetrafluoro-1-propene in said organicextracting agent at infinite dilution, and P2 represents the saturatingvapor pressure of trans-1,3,3,3-tetrafluoro-1-propene. Said organicextracting agent may have an absorption capacity C_(2,S) of greater thanor equal to 0.2, said absorption capacity being calculated by theformula C_(2,S)=1/(γ_(2,S)) in which γ_(2,S) represents the activitycoefficient in said organic extracting agent at infinite dilution. Thus,to separate out a first azeotropic or quasi-azeotropic compositioncomprising 2,3,3,3-tetrafluoro-1-propene andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), an organic extractingagent with a separation factor S_(1,2) of greater than or equal to 1.1and an absorption capacity C_(2,S) of greater than or equal to 0.2 maybe used; said organic extracting agent may thus be chloroethane,3-chloro-1,1,1,2,2,3-hexafluoropropane,1,1,1,2,2,3,3,4,4-nonafluorobutane,2-chloro-1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-pentafluoropropane,ethylamine, bromofluoromethane, 1-bromo-1,2-difluoroethylene,1-chloro-1,1,2,3,3,3-hexafluoropropane,1-chloro-1,1,2,2-tetrafluoropropane, acetaldehyde,1-chloro-1,1,2,2,3,3-hexafluoropropane, 1,1,1-trifluoro-2-propanone,2-chloro-1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane,trichlorofluoromethane, 1-chloro-1,1-difluoropropane,1,1,1-trifluoro-2-bromoethane, 1,1-dichloro-2,2,2-trifluoroethane,1-chloro-2,2,3,3,3-pentafluoropropane,1,2-dichloro-1,1,2-trifluoroethane, 2,2,2-trifluoroethyl methyl ether,1,1-dichloroethylene, furan, methyl formate, isopropylamine,1,1,2,2-tetrafluoroethyl methyl ether, 1,1,1,2,3,4,4,4-octafluorobutane,2-methoxy-1-propene, heptafluoro-1-methoxypropane, diethyl ether,1,2-epoxypropane, ethanethiol, 2-chloro-2-fluoropropane, ethoxyethene,1-chloro-2,2-difluoroethane, ethylmethylamine, dimethyl sulfide,2-chloropropane, bromoethane, dichloromethane, dimethoxymethane,2-chloro-1,1,1,3,3-pentafluoropropane, 1-chloro-1,2,2-trifluoropropane,iodomethane, 2,2-dichloro-1,1,1,3,3-pentafluoropropane,2-amino-2-methylpropane, methyl cyclopropyl ether, 3-chloropropene,3-chloro-1,1,1-trifluoropropane, 1,1,1-trichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2-difluoroethane,1,2-dichloro-1,1,2,3,3-pentafluoropropane, n-propylamine,1,1,2-trichloro-1,2,2-trifluoroethane, 2,2-dimethylbutane,isopropylmethylamine, ethanedial,1,2-dichloro-1,1,3,3,3-pentafluoropropane,1-chloro-1,2,2,3-tetrafluoropropane, perfluorocyclohexane,1,1-dichloro-1,2,2,3,3-pentafluoropropane, 2-chloro-2-methylpropane,3-chloro-1,1,1,3-tetrafluoropropane,2,3-dichloro-1,1,1,2,3-pentafluoropropane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-propanethiol,1,3-dichloro-1,1,2,3,3-pentafluoropropane,1,2-dichloro-3,3,3-trifluoropropene,1,3-dichloro-1,1,2,2,3-pentafluoropropane,1,1,1,2,2,3,4,5,5,5-decafluoropentane, 2-ethoxypropane,2,2-dichloro-1,1,1,3-tetrafluoropropane, 1-chloro-2,2-difluoropropane,methyl t-butyl ether, diethylamine, propanone, perfluoro-n-hexane,methyl acetate, 1,1-dichloroethane, ethyl 1,1,2,2-tetrafluoroethylether, 4-methoxy-2-methyl-2-butanethiol, 2-bromopropane,chloromethoxymethane, 1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane,1,1-dichloro-2,2-difluoroethane,2,2-dichloro-1,1,3,3-tetrafluoropropane, difluorodiethylsilane,2-butanamine, 2,3-dichloro-1,1,1,2-tetrafluoropropane,n-methylpropylamine, 3-methylpentane,1,1-dichloro-1,2,2,3-tetrafluoropropane, tert-butylthiol, isobutanal,methanol, tetrahydrofuran, 1,3-dichloro-1,1,2,2-tetrafluoropropane,1,1,1-trichloro-2,2-difluoroethane,1,2-dichloro-1,2,3,3-tetrafluoropropane, 1-propanethiol,chlorobromomethane, 2-chlorobutane, isopropyl formate, diisopropylether, 1,3-dichloro-1,1,3,3-tetrafluoropropane, hexane,1,3-dichloro-1,2,2,3-tetrafluoropropane,1,2-dichloro-1,1,2,3-tetrafluoropropane, 3-bromopropene,2,3-dichloro-1,1,1,3-tetrafluoropropane, 1,1-dichloro-2-fluoroethane,1-bromopropane, 1,1-difluoro-1,2,2-trichloroethane,1,1,2-trichloro-1,2-difluoroethane, methylglyoxal, iodoethane,2-ethoxy-2-methylpropane, 2-bromo-2-methylpropane,1,2-dichloro-1-fluoroethane, 1,1,1-trichloroethane,2,2,2-trifluoroethanol, 1-chloro-3-fluoropropane,1,1,1-trifluoro-2-propanol, 2,3-dichloro-1,1,1-trifluoropropane,perfluoromethylcyclohexane, ethyl acetate, 1-butylamine, 1-chlorobutane,ethanol, butanone, 2,4-dimethylpentane, cyclohexane, n-propyl formate,2-ethoxybutane, acetonitrile, pentafluoro-1-propanol, 2-propanol,tert-butanol, perfluoroheptane, 1,3-dichloro-1,1,2-trifluoropropane,1-methoxy-2-methylbutane, 1,1-dichloro-2,2,3-trifluoropropane,cyclohexene, 2,2-dimethoxypropane,1,3,3-trichloro-1,1,2,2-tetrafluoropropane, 2-chloro-2-methylbutane,1,2-dichloroethane, 1-ethoxy-2-methylpropane, diisopropylamine,thiophene, 2-butanethiol, 1,1,1-trichloro-2,2,3,3-tetrafluoropropane,1,2-dimethoxyethane, 3-methyl-2-butanamine,1,1,3-trichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,2,2-trifluoropropane, diethoxymethane,1,1-dichloropropane, 2-methyl-1-propanethiol,1,2-dichloro-2-fluoropropane, isopropyl acetate, 2-iodopropane,di-n-propyl ether, 3-pentylamine, n-methylbutylamine, 2-bromobutane,2,2-difluorotetrachloroethane, diethyl sulfide, 1-ethoxybutane,1,1,2,2-tetrachloro-1,2-difluoroethane, 1-fluorohexane,1-methoxy-2-propanamine, 1,3-dichloro-1,2,3-trifluoropropane,2,3-dichloro-1-propene, 2-methoxyethanamine, 2,2-difluoroethanol,2-methylbutanal, 1,2-dichloropropane, propanol, tert-butyl acetate,propionitrile, 3-chloropentane, trichloroacetaldehyde,2-allyloxyethanol, butanethiol, isoamyl chloride, 1-methoxypentane,ethyl propionate, 2-butanol, 1,2-dimethoxypropane, isopropyl isobutylether, 1,1,1-trichloro-2,2,3-trifluoropropane, methylcyclohexane,1-chloro-4-fluorobutane, 1-bromo-3-fluoropropane,2,4,4-trimethyl-1-pentene, dioxane, 1-bromobutane, 3-pentanone,1,1,2-trichloro-2-fluoroethane, 1,1-diethoxyethane, 2-pentanone,2-methyl-2-butanol, 1-iodopropane, 2-methoxy-1-propanamine,1,1,3-trichloro-1,2,2-trifluoropropane,1,1,3-trichloro-2,2,3-trifluoropropane, trimethoxymethane,cis-1,3-dichloropropene, 2,2-dichlorobutane, n-pentylamine,1,1-dichloro-2,2-difluoroethyl methyl ether, 2,2,4-trimethyl-2-pentene,perfluorooctane, 1,1,1,2-tetrachloro-2-fluoroethane, 1,3-dioxane,3,3-dimethyl-2-butanone, piperidine, 1-bromo-2-chloroethane, isobutanol,2-bromo-2-methylbutane, dipropylamine, 2,2,3,3-tetraflouro-1-propanol,2-ethoxyethanamine, triethylfluorosilane, 1-methylcyclohexene, toluene,trans-1,3-dichloropropene, sec-butyl acetate, 2-fluorotoluene,2,2-dimethyl-1-propanol, 1,1,1-trichloro-3-fluoropropane,n-methyl-1,2-ethanediamine, 2,2-diethoxypropane, 1,3,5-trioxane,3,3,3-trichloro-1-propene, 1-chloro-3,3-dimethylbutane, pyridine,2,3-dimethylhexane, 1,1,1,2-tetrachloro-3,3,3-trifluoropropane,n-methylmorpholine, 3-pentanol, 4-methyl-2-pentanone, 1,2-diaminoethane,isobutyl tert-butyl ether, 2-bromopentane, butyronitrile, 1-butanol,2,3-dichlorobutane, sec-butyl tert-butyl ether, 1-methoxy-2-propanol,1,1,3,3-tetrachloro-1,2,2-trifluoropropane, 1,2-propanediamine,2,6-dimethyl-5-heptenal, perfluorobutanoic acid,1,1,1,3-tetrachloro-2,2,3-trifluoropropane, 1-bromo-3-methylbutane,1,3-dichloro-trans-2-butene, 1,3-dichloropropane,1-(dimethylamino)-2-propanol, tetrahydrothiophene, 3-methyl-3-pentanol,1,2-dibromo-1-fluoroethane, 1,1-diethoxypropane, 1,2,2-trichloropropane,1-chloro-2-methyl-2-propanol, 2-methoxyethanol, 1,2-dichlorobutane,4,4,4-trifluorobutanol, 2-ethylbutylamine, perfluorononane, octane,diethyl carbonate, n-butyl acetate, 1-pentanethiol,1,2,2,3-tetrachloro-3,3-difluoropropane, 2-chloro-1,1-dimethoxyethane,2-hexanone, n-ethylethylenediamine, 3-fluoropropanol, 5-hexen-2-one,2,3-dichloro-2-methylbutane, 1,1-diethoxy-n,n-dimethylmethanamine,2-methylpyridine, 1-bromopentane, 2-methoxyl-propanol,1,2-dichloro-2-butene, 1-iodobutane, 1-ethoxy-2-propanol, hexanal,4-methyl-2-pentanol, 1,2-dibromoethane, chlorobenzene, ethylcyclohexane,perfluorooctyl bromide, bromoacetic acid methyl ester,1,1,2-trichloropropane, 1,2-octanediol, 4-methyl-2-hexanamine,hexylamine, 2-chloro-1-propanol, 2-(dimethylamino)ethanol,1,3-dichlorobutane, cyclohexylamine, n-ethyl-2-dimethylaminoethylamine,ethoxyethanol, 3-hexanol, 2-hexanol, ethylbenzene, 2-methylpyrazine,2-ethoxy-1-propanol, 1-pentanol, 1-methylpiperazine, n-ethylmorpholine,1,4-dimethylbenzene, 1,3-dimethylbenzene, 1,3-propanediamine, di-n-butylether, 3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile,(methyleneamino)acetonitrile, 1,2-dibromopropane, 2-heptanamine,1,2,3-trichloropropene, 1,2,3-trimethylcyclohexane, 2,3-dimethylbutanol,1-ethoxyhexane, 1-chloro-3-bromopropane, perfluoro-n-decane, 3-furfural,n,n-diethylethylenediamine, 2,6-dimethylpyridine,1,1,3,3-tetrachloro-1-fluoropropane, 4-methyl-2-hexanone,1,2-dimethylbenzene, 1,1,2,2,3-pentchloro-3,3-difluoropropane,1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane, styrene,4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, 2-ethyl-1-butanol, 1,2-dichloropentane,2-methyl-1-pentanol, methyl hexanoate, 2-propoxyethanol,dimethylethanolamine or 1-propoxy-2-propanol. Advantageously, saidorganic extracting agent may have a separation factor 51.2 of greaterthan or equal to 1.2 and/or an absorption capacity C_(2,S) of greaterthan or equal to 0.40; and said organic extracting agent may thus bechloroethane, 3-chloro-1,1,1,2,2,3-hexafluoropropane,1,1,1,2,2,3,3,4,4-nonafluorobutane,2-chloro-1,1,1,3,3,3-hexafluoropropane, 1,1,1,3,3-pentafluoropropane,ethylamine, bromofluoromethane, 1-bromo-1,2-difluoroethylene,1-chloro-1,1,2,3,3,3-hexafluoropropane,1-chloro-1,1,2,2-tetrafluoropropane, acetaldehyde,1-chloro-1,1,2,2,3,3-hexafluoropropane, 1,1,1-trifluoro-2-propanone,2-chloro-1,1,1,2-tetrafluoropropane, 1,1,1,2,3-pentafluoropropane,1-chloro-1,1-difluoropropane, 1,1,1-trifluoro-2-bromoethane,1,1-dichloro-2,2,2-trifluoroethane,1-chloro-2,2,3,3,3-pentafluoropropane,1,2-dichloro-1,1,2-trifluoroethane, 2,2,2-trifluoroethyl methyl ether,furan, methyl formate, isopropylamine, 1,1,2,2-tetrafluoroethyl methylether, 1,1,1,2,3,4,4,4-octafluorobutane, 2-methoxy-1-propene,heptafluoro-1-methoxypropane, diethyl ether, 1,2-epoxypropane,ethanethiol, 2-chloro-2-fluoropropane, ethoxyethene,1-chloro-2,2-difluoroethane, ethylmethylamine, dimethyl sulfide,2-chloropropane, bromoethane, dimethoxymethane,2-chloro-1,1,1,3,3-pentafluoropropane, 1-chloro-1,2,2-trifluoropropane,2,2-dichloro-1,1,1,3,3-pentafluoropropane, 2-amino-2-methylpropane,methyl cyclopropyl ether, 3-chloropropene,3-chloro-1,1,1-trifluoropropane, 1,1,1-trichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2-difluoroethane,1,2-dichloro-1,1,2,3,3-pentafluoropropane, n-propylamine,1,1,2-trichloro-1,2,2-trifluoroethane, isopropylmethylamine, ethanedial,1,2-dichloro-1,1,3,3,3-pentafluoropropane,1-chloro-1,2,2,3-tetrafluoropropane, perfluorocyclohexane,1,1-dichloro-1,2,2,3,3-pentafluoropropane, 2-chloro-2-methylpropane,3-chloro-1,1,1,3-tetrafluoropropane,2,3-dichloro-1,1,1,2,3-pentafluoropropane,1,1-dichloro-2,2,3,3,3-pentafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-propanethiol,1,2-dichloro-3,3,3-trifluoropropene,1,1,1,2,2,3,4,5,5,5-decafluoropentane, 2-ethoxypropane,2,2-dichloro-1,1,1,3-tetrafluoropropane, 1-chloro-2,2-difluoropropane,methyl t-butyl ether, diethylamine, propanone, perfluoro-n-hexane,methyl acetate, ethyl 1,1,2,2-tetrafluoroethyl ether,4-methoxy-2-methyl-2-butanethiol, 2-bromopropane,1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane,1,1-dichloro-2,2-difluoroethane,2,2-dichloro-1,1,3,3-tetrafluoropropane, difluorodiethylsilane,2-butanamine, 2,3-dichloro-1,1,1,2-tetrafluoropropane,n-methylpropylamine, 1,1-dichloro-1,2,2,3-tetrafluoropropane,tert-butylthiol, isobutanal, tetrahydrofuran,1,3-dichloro-1,1,2,2-tetrafluoropropane,1,1,1-trichloro-2,2-difluoroethane,1,2-dichloro-1,2,3,3-tetrafluoropropane, 1-propanethiol, 2-chlorobutane,isopropyl formate, diisopropyl ether,1,3-dichloro-1,2,2,3-tetrafluoropropane,1,2-dichloro-1,1,2,3-tetrafluoropropane,2,3-dichloro-1,1,1,3-tetrafluoropropane, 1-bromopropane,1,1-difluoro-1,2,2-trichloroethane, 1,1,2-trichloro-1,2-difluoroethane,methylglyoxal, 2-ethoxy-2-methylpropane, 2-bromo-2-methylpropane,1-chloro-3-fluoropropane, 1,1,1-trifluoro-2-propanol,2,3-dichloro-1,1,1-trifluoropropane, perfluoromethylcyclohexane, ethylacetate, 1-butylamine, 1-chlorobutane, butanone, n-propyl formate,2-ethoxybutane, pentafluoro-1-propanol, 2-propanol, tert-butanol,perfluoroheptane, 1,3-dichloro-1,1,2-trifluoropropane,1-methoxy-2-methylbutane, 1,1-dichloro-2,2,3-trifluoropropane,cyclohexene, 2,2-dimethoxypropane,1,3,3-trichloro-1,1,2,2-tetrafluoropropane, 2-chloro-2-methylbutane,1-ethoxy-2-methylpropane, diisopropylamine, 2-butanethiol,1,1,1-trichloro-2,2,3,3-tetrafluoropropane, 1,2-dimethoxyethane,3-methyl-2-butanamine, 1,1,3-trichloro-1,2,2,3-tetrafluoropropane,1,3-dichloro-1,2,2-trifluoropropane, diethoxymethane,2-methyl-1-propanethiol, isopropyl acetate, 2-iodopropane, di-n-propylether, 3-pentylamine, n-methylbutylamine, 2-bromobutane, diethylsulfide, 1-ethoxybutane, 1-fluorohexane, 1-methoxy-2-propanamine,1,3-dichloro-1,2,3-trifluoropropane, 2-methoxyethanamine,2-methylbutanal, propanol, tert-butyl acetate, propionitrile,3-chloropentane, 2-allyloxyethanol, butanethiol, isoamyl chloride,1-methoxypentane, ethyl propionate, 2-butanol, 1,2-dimethoxypropane,isopropyl isobutyl ether, 1,1,1-trichloro-2,2,3-trifluoropropane,1-chloro-4-fluorobutane, 1-bromo-3-fluoropropane,2,4,4-trimethyl-1-pentene, dioxane, 1-bromobutane, 3-pentanone,1,1-diethoxyethane, 2-pentanone, 2-methyl-2-butanol,2-methoxy-1-propanamine, 1,1,3-trichloro-1,2,2-trifluoropropane,1,1,3-trichloro-2,2,3-trifluoropropane, trimethoxymethane,n-pentylamine, 1,1-dichloro-2,2-difluoroethyl methyl ether,2,2,4-trimethyl-2-pentene, perfluorooctane, 1,3-dioxane,3,3-dimethyl-2-butanone, piperidine, isobutanol, 2-bromo-2-methylbutane,dipropylamine, 2,2,3,3-tetraflouro-1-propanol, 2-ethoxyethanamine,triethylfluorosilane, 1-methylcyclohexene, toluene, sec-butyl acetate,2-fluorotoluene, 2,2-dimethyl-1-propanol, n-methyl-1,2-ethanediamine,2,2-diethoxypropane, 1,3,5-trioxane, 1-chloro-3,3-dimethylbutane,pyridine, 1,1,2-tetrachloro-3,3,3-trifluoropropane, n-methylmorpholine,3-pentanol, 4-methyl-2-pentanone, 1,2-diaminoethane, isobutyl tert-butylether, 2-bromopentane, butyronitrile, 1-butanol, sec-butyl tert-butylether, 1-methoxy-2-propanol, 1,1,3,3-tetrachloro-1,2,2-trifluoropropane,1,2-propanediamine, 2,6-dimethyl-5-heptenal, perfluorobutanoic acid,1,1,1,3-tetrachloro-2,2,3-trifluoropropane, 1-bromo-3-methylbutane,1-(dimethylamino)-2-propanol, tetrahydrothiophene, 3-methyl-3-pentanol,1,1-diethoxypropane, 2-methoxyethanol, 4,4,4-trifluorobutanol,2-ethylbutylamine, perfluorononane, diethyl carbonate, n-butyl acetate,1-pentanethiol, 2-chloro-1,1-dimethoxyethane, 2-hexanone,n-ethylethylenediamine, 5-hexen-2-one,1,1-diethoxy-n,n-dimethylmethanamine, 2-methylpyridine, 1-bromopentane,2-methoxy-1-propanol, 1-ethoxy-2-propanol, hexanal, 4-methyl-2-pentanol,perfluorooctyl bromide, 1,2-octanediol, 4-methyl-2-hexanamine,hexylamine, methoxycyclohexane, 2-(dimethylamino)ethanol,cyclohexylamine, n-ethyl-2-dimethylaminoethylamine, ethoxyethanol,3-hexanol, 2-hexanol, ethylbenzene, 2-methylpyrazine,2-ethoxy-1-propanol, 1-pentanol, 1-methylpiperazine, n-ethylmorpholine,1,4-dimethylbenzene, 1,3-dimethylbenzene, 1,3-propanediamine, di-n-butylether, 3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile,(methyleneamino)acetonitrile, 2-heptanamine, 2,3-dimethylbutanol,1-ethoxyhexane, perfluoro-n-decane, 3-furfural,n,n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methyl-2-hexanone,1,2-dimethylbenzene, 1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane,styrene, 4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, 2-ethyl-1-butanol, 2-methyl-1-pentanol, methylhexanoate, 2-propoxyethanol, dimethylethanolamine or1-propoxy-2-propanol.

Preferably, said organic extracting agent may have a separation factorS_(1,2) of greater than or equal to 1.4 and/or an absorption capacityC_(2,S) of greater than or equal to 0.6; and said organic extractingagent may thus be ethylamine, acetaldehyde,1,1,1,3,3-pentafluoropropane, 1,1,1-trifluoro-2-propanone,1,1,1,2,3-pentafluoropropane, 2,2,2-trifluoroethyl methyl ether, methylformate, isopropylamine, 1,1,2,2-tetrafluoroethyl methyl ether,2-methoxy-1-propene, diethyl ether, 1,2-epoxypropane, ethoxyethene,ethylmethylamine, dimethoxymethane, 1-chloro-1,2,2-trifluoropropane,2-amino-2-methylpropane, methyl cyclopropyl ether,3-chloro-1,1,1-trifluoropropane, n-propylamine, isopropylmethylamine,ethanedial, 1-chloro-1,2,2,3-tetrafluoropropane,3-chloro-1,1,1,3-tetrafluoropropane,2-chloro-1,1,1,3-tetrafluoropropane, 2-ethoxypropane, methyl t-butylether, diethylamine, propanone, methyl acetate, ethyl1,1,2,2-tetrafluoroethyl ether, 4-methoxy-2-methyl-2-butanethiol,difluorodiethylsilane, 2-butanamine, n-methylpropylamine, isobutanal,tetrahydrofuran, 1,3-dichloro-1,1,2,2-tetrafluoropropane, isopropylformate, diisopropyl ether, methylglyoxal, 2-ethoxy-2-methylpropane,2,3-dichloro-1,1,1-trifluoropropane, ethyl acetate, 1-butylamine,butanone, n-propyl formate, 2-ethoxybutane,1,3-dichloro-1,1,2-trifluoropropane, 1-methoxy-2-methylbutane,1,1-dichloro-2,2,3-trifluoropropane, 2,2-dimethoxypropane,1-ethoxy-2-methylpropane, diisopropylamine, 1,2-dimethoxyethane,3-methyl-2-butanamine, 1,3-dichloro-1,2,2-trifluoropropane,diethoxymethane, isopropyl acetate, di-n-propyl ether, 3-pentylamine,n-methylbutylamine, diethyl sulfide, 1-ethoxybutane, 1-fluorohexane,1-methoxy-2-propanamine, 1,3-dichloro-1,2,3-trifluoropropane,2-methoxyethanamine, 2-methylbutanal, tert-butyl acetate, propionitrile,2-allyloxyethanol, 1-methoxypentane, ethyl propionate,1,2-dimethoxypropane, isopropyl isobutyl ether, dioxane, 3-pentanone,1,1-diethoxyethane, 2-pentanone, 2-methoxy-1-propanamine,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,piperidine, dipropylamine, 2-ethoxyethanamine, triethylfluorosilane,sec-butyl acetate, n-methyl-1,2-ethanediamine, 2,2-diethoxypropane,pyridine, n-methylmorpholine, 4-methyl-2-pentanone, 1,2-diaminoethane,isobutyl tert-butyl ether, butyronitrile, sec-butyl tert-butyl ether,1-methoxy-2-propanol, 1,2-propanediamine, 2,6-dimethyl-5-heptenal,perfluorobutanoic acid, 1-(dimethylamino)-2-propanol,3-methyl-3-pentanol, 1,1-diethoxypropane, 2-ethylbutylamine, diethylcarbonate, n-butyl acetate, 2-hexanone, n-ethylethylenediamine,5-hexen-2-one, 1,1-diethoxy-n,n-dimethylmethanamine, 2-methylpyridine,2-methoxy-1-propanol, 1-ethoxy-2-propanol, hexanal,4-methyl-2-hexanamine, hexylamine, methoxycyclohexane,2-(dimethylamino)ethanol, cyclohexylamine,n-ethyl-2-dimethylaminoethylamine, ethoxyethanol, 2-methylpyrazine,2-ethoxy-1-propanol, 1-methylpiperazine, n-ethylmorpholine,1,3-propanediamine, di-n-butyl ether,3,3,4,4,5,5,6,6-octafluoro-1-pentanol, valeronitrile, 2-heptanamine,1-ethoxyhexane, n,n-diethylethylenediamine, 2,6-dimethylpyridine,4-methyl-2-hexanone, 1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane,4-methylpyridine, n,n′-diethyl-1,2-ethanediamine,2,6-dimethylmorpholine, methyl hexanoate, 2-propoxyethanol or1-propoxy-2-propanol.

In particular, said organic extracting agent may have a separationfactor S_(1,2) of greater than or equal to 1.6 and/or an absorptioncapacity C_(2,S) of greater than or equal to 0.80; and said organicextracting agent may thus be ethylamine, 1,1,1-trifluoro-2-propanone,methyl formate, isopropylamine, 2-methoxy-1-propene, diethyl ether,1,2-epoxypropane, ethoxyethene, ethylmethylamine, dimethoxymethane,2-amino-2-methylpropane, methyl cyclopropyl ether, n-propylamine,isopropylmethylamine, 2-ethoxypropane, methyl t-butyl ether,diethylamine, propanone, methyl acetate, 2-butanamine,n-methylpropylamine, isobutanal, tetrahydrofuran, isopropyl formate,diisopropyl ether, 2-ethoxy-2-methylpropane, ethyl acetate,1-butylamine, butanone, n-propyl formate, 2-ethoxybutane,1-methoxy-2-methylbutane, 2,2-dimethoxypropane,1-ethoxy-2-methylpropane, 1,2-dimethoxyethane, 3-methyl-2-butanamine,diethoxymethane, isopropyl acetate, di-n-propyl ether, 3-pentylamine, n,methylbutylamine, 1-ethoxybutane, 1-methoxy-2-propanamine,2-methoxyethanamine, 2-methylbutanal, tert-butyl acetate,1-methoxypentane, ethyl propionate, 1,2-dimethoxypropane, dioxane,3-pentanone, 1,1-diethoxyethane, 2-pentanone, 2-methoxy-1-propanamine,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,piperidine, 2-ethoxyethanamine, sec-butyl acetate,n-methyl-1,2-ethanediamine, 2,2-diethoxypropane, 4-methyl-2-pentanone,1,2-diaminoethane, butyronitrile, 1-methoxy-2-propanol,1,2-propanediamine, 2,6-dimethyl-5-heptenal,1-(dimethylamino)-2-propanol, 1,1-diethoxypropane, 2-ethylbutylamine,diethyl carbonate, n-butyl acetate, 2-hexanone, n-ethylethylenediamine,5-hexen-2-one, 2-methylpyridine, 2-methoxy-1-propanol,1-ethoxy-2-propanol, hexanal, 4-methyl-2-hexanamine, hexylamine,methoxycyclohexane, 2-(dimethylamino)ethanol, cyclohexylamine,n-ethyl-2-dimethylaminoethylamine, 2-methylpyrazine,2-ethoxy-1-propanol, 1-methylpiperazine, 1,3-propanediamine, di-n-butylether, valeronitrile, 2-heptanamine, 1-ethoxyhexane,n,n-diethylethylenediamine, 2,6-dimethylpyridine, 4-methyl-2-hexanone,1-methoxy-2-acetoxypropane, 1,1,1-triethoxyethane, 4-methylpyridine,n,n′-diethyl-1,2-ethanediamine, 2,6-dimethylmorpholine, methylhexanoate, 2-propoxyethanol or 1-propoxy-2-propanol. Said organicextracting agent may have a separation factor S_(1,2) of greater than orequal to 1.6 and/or an absorption capacity C_(2,S) of greater than orequal to 0.80; and may be chosen from ethylamine, isopropylamine,diethyl ether, ethoxyethene, dimethoxymethane, n-propylamine, methylt-butyl ether, diethylamine, propanone, methyl acetate, isobutanal,tetrahydrofuran, isopropyl formate, diisopropyl ether,2-ethoxy-2-methylpropane, ethyl acetate, butanone, diethoxymethane,isopropyl acetate, 3-pentylamine, 2-methoxyethanamine, tert-butylacetate, dioxane, 3-pentanone, 1,1-diethoxyethane, 2-pentanone,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,sec-butyl acetate, 4-methyl-2-pentanone, 1,2-diaminoethane,1-methoxy-2-propanol, diethyl carbonate, n-butyl acetate,1-ethoxy-2-propanol and hexanal. Advantageously, said organic extractingagent may have a separation factor S_(1,2) of greater than or equal to1.6 and/or an absorption capacity C_(2,S) of greater than or equal to0.80; and may be chosen from ethylamine, isopropylamine, diethyl ether,dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, butanone, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal. Preferably, said organic extractingagent may have a separation factor S_(1,2) of greater than or equal to1.6 and/or an absorption capacity C_(2,S) of greater than or equal to0.80; and may be chosen from ethylamine, isopropylamine, diethyl ether,dimethoxymethane, n-propylamine, diethylamine, diisopropyl ether,2-ethoxy-2-methylpropane, diethoxymethane, isopropyl acetate,3-pentylamine, 2-methoxyethanamine, tert-butyl acetate, dioxane,trimethoxymethane, n-pentylamine, 1,3-dioxane, sec-butyl acetate,1,2-diaminoethane, 1-methoxy-2-propanol, n-butyl acetate,1-ethoxy-2-propanol and hexanal.

According to a preferred embodiment, said third composition comprisingsaid organic extracting agent and said at least one compound chosen fromthe group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E); preferably, the third composition comprising said organicextracting agent and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) andoptionally or not at least one compound chosen from the group consistingof 1,1-difluoroethane (152a) and chloropentafluoroethane (115); may besubjected to distillation to separate, on the one hand, the organicextracting agent and, on the other hand, said at least one compoundchosen from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E); preferably to separate, on the one hand, the organicextracting agent and, on the other hand,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or not atleast one compound chosen from the group consisting of1,1-difluoroethane (152a) and chloropentafluoroethane (115).

According to a particular embodiment, the stream comprising2,3,3,3-tetrafluoropropene separated out in step b) of the presentprocess is subsequently purified or liquefied and stored. According tothis embodiment, traces of organic extracting agent may be present inthe stream comprising 2,3,3,3-tetrafluoropropene. The traces of organicextracting agent in said stream are less than 10 ppm, preferably lessthan 1 ppm, in particular less than 500 ppb and more particularly lessthan 100 ppb.

The present process thus makes it possible to purify2,3,3,3-tetrafluoro-1-propene. Advantageously, the content of at leastone compound chosen from the group consisting of 1,1-difluoroethane(152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in the stream comprising2,3,3,3-tetrafluoro-1-propene, obtained in step b) of the presentpurification process, is less than the content of that or those in saidfirst composition. Preferably, the content oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in the stream comprising2,3,3,3-tetrafluoro-1-propene, obtained in step b) of the present purepurification process is less than the content oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said firstcomposition.

For example, the content of any one of the compounds may be reduced by50%, advantageously by 75%, preferably by 90%, in particular by 95% andmore particularly by 98%. Advantageously, the content of at least two orof all of said compounds chosen from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) may be reduced by 50%,advantageously by 75%, preferably by 90%, in particular by 95% and moreparticularly by 98%. Preferably, the content oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) may be reduced by 50%,advantageously by 75%, preferably by 90%, in particular by 95% and moreparticularly by 98%. The contents are expressed as weight percentages.

Preferably, the stream comprising 2,3,3,3-tetrafluoro-1-propene obtainedin step b) of the present purification process may be free of at leastone, at least two or of all of the compounds chosen from the groupconsisting of 1,1-difluoroethane (152a), chloropentafluoroethane (115)and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) when this or thesecompounds are present in said first composition. In particular, thestream comprising 2,3,3,3-tetrafluoro-1-propene obtained in step b) ofthe present purification process may be free oftrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E). The term “free of” meansthat the stream comprising 2,3,3,3-tetrafluoro-1-propene (1234yf)comprises less than 50 ppm, advantageously less than 20 ppm andpreferably less than 10 ppm of the compound under consideration relativeto the total weight of the stream.

According to a preferred embodiment, said first composition used in stepa) of the present process may be purified before being used.Specifically, if said first composition comprises impurities with aboiling point below the boiling point of 2,3,3,3-tetrafluoro-1-propeneand optionally heavy impurities, the process may comprise, prior to stepa), the following steps:

-   -   i′) use or provision of a composition comprising        2,3,3,3-tetrafluoro-1-propene, impurities with a boiling point        below the boiling point of 2,3,3,3-tetrafluoro-1-propene, and at        least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), preferably        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or        not at least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115), and        optionally heavy impurities;    -   ii′) distillation of said composition from step i) to remove, at        the top of the column, impurities with a boiling point below the        boiling point of 2,3,3,3-tetrafluoro-1-propene and to form a        first stream comprising 2,3,3,3-tetrafluoro-1-propene and at        least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), preferably a        first stream comprising 2,3,3,3-tetrafluoro-1-propene,        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or        not at least one compound chosen from the group consisting of        1,1-difluoroethane (152a), chloropentafluoroethane (115), and        optionally heavy impurities, recovered at the bottom of the        distillation column;    -   iii′) optionally, distillation of said first stream recovered at        the bottom of the distillation column in step ii′) to recover,        at the top of the column, a second stream comprising        2,3,3,3-tetrafluoro-1-propene and at least one compound chosen        from the group consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); preferably a        second stream comprising 2,3,3,3-tetrafluoro-1-propene,        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or        not at least one compound chosen from the group consisting of        1,1-difluoroethane (152a) and chloropentafluoroethane (115);        and, at the bottom of the distillation column, a stream        comprising the heavy impurities;    -   said at first stream recovered in step ii′) or said second        stream recovered in step iii′) corresponds to said first        composition used in step a).

The heavy impurities are as defined above in the present patentapplication.

According to a second aspect, the present invention provides a processfor producing 2,3,3,3-tetrafluoro-1-propene. In addition, this processmay include the purification thereof. Thus, the present inventionprovides a process for producing 2,3,3,3-tetrafluoro-1-propene,comprising the steps of:

-   -   A) fluorination in the presence of a catalyst for a compound of        formula (I) CX(Y)₂—CX(Y)_(m)—CH_(m)XY in which X and Y        independently represent a hydrogen, fluorine or chlorine atom        and m=0 or 1 and/or fluorination in the presence of a catalyst        for a compound of formula        (CX_(n)Y_(3-n))CH_(p)X_(1-p)CH_(m)X_(2-m) (II) in which X is,        independently of each other, Cl, F, I or Br; Y is, independently        of each other, H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1        or 2; and p is 0 or 1;    -   B) recovery of a stream comprising 2,3,3,3-tetrafluoro-1-propene        and at least one of the compounds chosen from the group        consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), preferably a        stream comprising 2,3,3,3-tetrafluoro-1-propene,        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or        not at least one compound chosen from the group consisting of        1,1-difluoroethane (152a) and chloropentafluoroethane (115);    -   C) implementation of the process for purifying        2,3,3,3-tetrafluoro-1-propene according to the present invention        using the stream recovered in step B).

According to a preferred embodiment, the process for producing2,3,3,3-tetrafluoro-1-propene comprising the steps of:

-   -   A) fluorination in the presence of a catalyst for a compound of        formula (I) CX(Y)₂—CX(Y)_(m)—CH_(m)XY in which X and Y        independently represent a hydrogen, fluorine or chlorine atom        and m=0 or 1 and/or fluorination in the presence of a catalyst        for a compound of formula        (CX_(n)Y_(3-n))CH_(p)X_(1-p)CH_(m)X_(2-m) (II) in which X is,        independently of each other, Cl, F, I or Br; Y is, independently        of each other, H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1        or 2; and p is 0 or 1;    -   B) recovery of a stream comprising 2,3,3,3-tetrafluoro-1-propene        and at least one of the compounds chosen from the group        consisting of 1,1-difluoroethane (152a),        chloropentafluoroethane (115) and        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), preferably a        stream comprising 2,3,3,3-tetrafluoro-1-propene,        trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or        not at least one compound chosen from the group consisting of        1,1-difluoroethane (152a) and chloropentafluoroethane (115);    -   C) implementation of the process for purifying        2,3,3,3-tetrafluoro-1-propene using the stream recovered in        step B) and comprising the steps of:        -   a) placing said first composition in contact with at least            one organic extracting agent to form a second composition;        -   b) extractive distillation of said second composition to            form:            -   i) a third composition comprising said organic                extracting agent and at least one of the compounds                chosen from the group consisting of 1,1-difluoroethane                (152a), chloropentafluoroethane (115) and                trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E),                preferably a third composition comprising said organic                extracting agent, trans-1,3,3,3-tetrafluoro-1-propene                (1234ze-E) and optionally or not at least one of the                compounds chosen from the group consisting of                1,1-difluoroethane (152a) and chloropentafluoroethane                (115); and            -   ii) a stream comprising 2,3,3,3-tetrafluoro-1-propene;        -   c) recovery and separation of said third composition to form            a stream comprising said organic extracting agent and a            stream comprising said at least one of the compounds chosen            from the group consisting of 1,1-difluoroethane (152a),            chloropentafluoroethane (115) and            trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); preferably,            a stream comprising said organic extracting agent and a            stream comprising trans-1,3,3,3-tetrafluoro-1-propene            (1234ze-E) and optionally or not at least one of the            compounds chosen from the group consisting of            1,1-difluoroethane (152a) and chloropentafluoroethane (115).

According to a particular embodiment, the stream recovered in step B) ofthe process for producing 2,3,3,3-tetrafluoro-1-propene may comprisehydrofluoric acid. In this case, prior to step C), the stream recoveredin step B) may undergo a preliminary distillation B1′) to remove HF atthe bottom of the distillation column. A stream comprising2,3,3,3-tetrafluoro-1-propene and at least one of the compounds chosenfrom the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), preferably a stream comprising2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one compound chosen from thegroup consisting of 1,1-difluoroethane (152a) andchloropentafluoroethane (115), is recovered at the top of thedistillation column. The latter stream recovered at the top of thedistillation column is then subjected to step C) of the process forproducing 2,3,3,3-tetrafluoro-1-propene.

According to a particular embodiment, the stream recovered in step B) ofthe process for producing 2,3,3,3-tetrafluoro-1-propene may compriseimpurities with a boiling point below the boiling point of2,3,3,3-tetrafluoro-1-propene. In this case, prior to step C), thestream recovered in step B) may undergo a preliminary distillation B2′),optionally subsequent to step B1′), to remove, at the top of thedistillation column, said impurities with a boiling point below theboiling point of 2,3,3,3-tetrafluoro-1-propene and to form a firststream comprising 2,3,3,3-tetrafluoro-1-propene and at least onecompound chosen from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), preferably a first stream comprising2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one compound chosen from thegroup consisting of 1,1-difluoroethane (152a), chloropentafluoroethane(115), recovered at the bottom of the distillation column. The latterstream recovered at the bottom of the distillation column is thensubjected to step C) of the process for producing2,3,3,3-tetrafluoro-1-propene.

According to a particular embodiment, the stream recovered in step B) ofthe process for producing 2,3,3,3-tetrafluoro-1-propene may compriseheavy impurities. In this case, prior to step C), the stream recoveredin step B) may undergo a preliminary distillation B3′), optionallysubsequent to step B1′) and/or B2′), to remove, at the bottom of thedistillation column, said heavy impurities; and to form a first streamcomprising 2,3,3,3-tetrafluoro-1-propene and at least one compoundchosen from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), preferably a first stream comprising2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one compound chosen from thegroup consisting of 1,1-difluoroethane (152a), chloropentafluoroethane(115), recovered at the top of the distillation column. The latterstream recovered at the top of the distillation column is then subjectedto step C) of the process for producing 2,3,3,3-tetrafluoro-1-propene.

According to a particular embodiment, the stream recovered in step B) ofthe process for producing 2,3,3,3-tetrafluoro-1-propene may alsocomprise HCl. The hydrochloric acid may be recovered by distillationbefore or after step B1′, independently of the other steps of theprocess.

More particularly, step A) is performed using1,1,2,3-tetrachloropropene, 2,3,3,3,-tetrachloropropene,1,1,3,3-tetrachloropropene, 1,3,3,3-tetrachloropropene,1,1,1,2,3-pentachloropropane, 1,1,1,3,3-pentachloropropane,1,1,2,2,3-pentachloropropane, 1,2-dichloro-3,3,3-trifluoropropane,2-chloro-2,3,3,3-tetrafluoropropane, 1,1,1,2,2-pentafluoropropane,1-chloro-1,3,3,3-tetrafluoropropane and 1,1,1,3,3-pentafluoropropane,preferably using 1,1,1,2,3-pentachloropropane,1,1,2,3,tetrachloropropene, 1,1,1,2,2-pentafluoropropane and/or2-chloro-3,3,3-trifluoro-1-propene; in particular using1,1,1,2,3-pentachloropropane (240db).

FIG. 1a schematically represents a simplified scheme of a device forperforming a process for purifying 2,3,3,3-tetrafluoro-1-propeneaccording to a particular embodiment of the invention. The mixturederived from the fluorination reaction, in the presence of a catalyst, acompound of formula (CX_(n)Y_(3-n))CHXCH_(m+1)X_(2-m) (I) and/orcatalytic fluorination, in the presence of a catalyst, a compound offormula (CX_(n)Y_(3-n))CH_(p)X_(1-p)═CH_(m)X_(2-m) (II) is obtained in1. In this particular embodiment, the mixture comprises2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and at least one of the compounds chosen from the groupconsisting of 1,1-difluoroethane (152a) and chloropentafluoroethane(115), impurities with a boiling point below the boiling point of2,3,3,3-tetrafluoro-1-propene and heavy impurities. The mixture istransferred into a distillation column 2 via pipe 3. The impurities witha boiling point below the boiling point of 2,3,3,3-tetrafluoro-1-propeneare recovered at the top of distillation column 2 and conveyed via pipe5 to an incinerator or a purification device 15. The residue obtained atthe bottom of the distillation column and comprising the otherconstituents of the mixture is conveyed to a second distillation column6 via pipe 4. The distillation performed in 6 is directed towardseparating the heavy impurities from the other constituents of themixture. The distillation operating conditions are thus suitable forthis purpose. The heavy impurities are recovered at the bottom of thedistillation column 8 and the other constituents are recovered at thetop of the distillation column and conveyed to the extractivedistillation column 9 via pipe 7. The extractive distillation performedin 9 is directed toward separating 2,3,3,3-tetrafluoro-1-propene fromthe other constituents of the mixture mentioned above. The extractivedistillation device 9 is fed with the organic extracting agent 17 chosenaccording to the method described in the present patent application.2,3,3,3-Tetrafluoro-1-propene is recovered at the top of the extractivedistillation column 9 and stored or purified in 10 via pipe 11. Themixture recovered at the bottom of the extractive distillation device 9especially comprises the organic extracting agent 17,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and at least one of thefollowing compounds: 1,1-difluoroethane (152a) orchloropentafluoroethane (115). The mixture recovered at the bottom ofthe extractive distillation device 9 is conveyed via pipe at 12 to adistillation device 13 which is directed toward separating the organicextracting agent from the other compounds present. The organicextracting agent is recovered at the bottom of the distillation deviceand recycled via pipe 16 to the extractive distillation device 9. Thecompounds recovered at the top of the distillation device 13 areconveyed via pipe 14 to pipe 5 to be incinerated or purified in 15.

The mixture provided in 1 may be free of impurities with a boiling pointbelow that of 2,3,3,3-tetrafluoro-1-propene. In this case, asillustrated in FIG. 1b , the mixture 1 is conveyed via pipe 3 to thedistillation column 6 to be processed as explained above in relationwith FIG. 1a . In another particular embodiment illustrated in FIG. 1c ,the mixture 1 may comprise 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and at least one of thefollowing compounds: 1,1-difluoroethane (152a) orchloropentafluoroethane (115). In this case, the mixture is conveyeddirectly to the extractive distillation column 9 to be processed thereinas explained above in relation with FIG. 1 a.

FIG. 2 schematically illustrates a device for performing a process forproducing 2,3,3,3-tetrafluoropropene according to a particularembodiment of the present invention. Hydrofluoric acid 21 is placed incontact with 1,1,1,2,3-pentachloropropane (240db) 22 in a reactor 23.The mixture obtained and comprising 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and at least one of thefollowing compounds: 1,1-difluoroethane (152a) orchloropentafluoroethane (115), is recovered at the reactor outlet andconveyed to a distillation column 25 via pipe 24. The mixture may alsocomprise HCl, HF and heavy impurities or impurities with a boiling pointbelow that of 2,3,3,3-tetrafluoro-1-propene. The stream obtained at thebottom of the distillation column comprising HF and optionally heavyimpurities is conveyed to the purification device 27 via pipe 26 topurify HF which will optionally be recycled in 23. The otherconstituents of the mixture are conveyed via pipe 28 to a purificationdevice 29 for purifying 2,3,3,3-tetrafluoro-1-propene. The purificationdevice 29 may be any of the devices illustrated in FIGS. 1a -1 b.

The catalyst used in the present process for producing2,3,3,3-tetrafluoropropene may be based, for example, on a metalcomprising a transition metal oxide or a derivative or a halide or anoxyhalide of such a metal. Mention may be made, for example, of FeCl₃,chromium oxyfluoride, chromium oxides (optionally subjected tofluorination treatments) and chromium fluorides, and mixtures thereof.Other possible catalysts are catalysts supported on carbon,antimony-based catalysts, and aluminum-based catalysts (for example AlF₃and Al₂O₃, aluminum oxyfluoride and aluminum fluoride).

Use may be made in general of a chromium oxyfluoride, an aluminumfluoride or oxyfluoride, or an optionally supported catalyst containinga metal such as Cr, Ni, Fe, Zn, Ti, V, Zr, Mo, Ge, Sn, Pb, Mg or Sb.

Reference may be made in this respect to WO 2007/079431 (on page 7,lines 1-5 and 28-32) and EP 939071 (paragraph [0022]), WO 2008/054781(on page 9, line 22 to page 10, line 34) and WO 2008/040969 (claim 1),to which reference is expressly made.

The catalyst is more particularly preferably chromium-based and it ismore particularly a mixed catalyst comprising chromium.

According to one embodiment, a mixed catalyst comprising chromium andnickel is used. The Cr/Ni mole ratio (on the basis of the metal element)is generally from 0.5 to 5, for example from 0.7 to 2, for exampleabout 1. The catalyst may contain from 0.5% to 20% by weight of nickel.

The metal may be present in metallic form or in the form of aderivative, for example an oxide, halide or oxyhalide. These derivativesare preferably obtained by activation of the catalytic metal.

The support is preferably constituted with aluminum, for examplealumina, activated alumina or aluminum derivatives, such as aluminumhalides and aluminum oxyhalides, for example described in U.S. Pat. No.4,902,838, or obtained via the activation process described above.

The catalyst may comprise chromium and nickel in an activated orunactivated form, on a support which has optionally been subjected toactivation.

Reference may be made to WO 2009/118628 (especially on page 4, line 30to page 7, line 16), to which reference is expressly made herein.

Another preferred embodiment is based on a mixed catalyst containingchromium and at least one element chosen from Mg and Zn. The atomicratio of Mg or Zn/Cr is preferably from 0.01 to 5.

Before its use, the catalyst is preferably subjected to activation withair, oxygen or chlorine and/or with HF.

The catalyst is preferably subjected to activation with air or oxygenand HF at a temperature from 100 to 500° C., preferably from 250 to 500°C. and more particularly from 300 to 400° C. The activation time ispreferably from 1 to 200 hours and more particularly from 1 to 50 hours.

This activation may be followed by a final fluorination activation stepin the presence of an oxidizing agent, HF and organic compounds.

The HF/organic compounds mole ratio is preferably from 2 to 40 and theoxidizing agent/organic compounds mole ratio is preferably from 0.04 to25. The temperature of the final activation is preferably from 300 to400′C and its duration is preferably from 6 to 100 hours.

The gas-phase fluorination reaction may be performed:

-   -   with an HF/compound of formula (I) and/or (II) mole ratio from        3:1 to 150:1, preferably from 4:1 to 125:1 and more particularly        preferably from 5:1 to 100:1;    -   with a contact time from 3 to 100 seconds, preferably 4 to 75        seconds and more particularly 5 to 50 seconds (volume of        catalyst divided by the total entering stream, adjusted to the        operating temperature and pressure);    -   at a pressure ranging from atmospheric pressure to 20 bar,        preferably from 2 to 18 bar and more particularly from 3 to 15        bar;    -   at a temperature (temperature of the catalytic bed) from 200 to        450° C., preferably from 250 to 400′C and more particularly from        280 to 380° C.

The duration of the reaction step is typically from 10 to 8000 hours,preferably from 50 to 5000 hours and more particularly preferably from70 to 1000 hours.

An oxidizing agent, preferably oxygen, may optionally be added duringthe fluorination reaction. The oxygen/organic compounds mole ratio maybe from 0.005 to 2, preferably from 0.01 to 1.5. Oxygen may beintroduced in pure form or in the form of air or an oxygen/nitrogenmixture. Oxygen may also be replaced with chlorine.

Method for Selecting the Organic Extracting Agent

The selection of the organic extracting agent is determined by using theCosmo-RS model implemented in the COSMOTHERM software. For this selectedbinary couple, a separation factor is calculated for each of thesolvents studied via the following equation:S _(1,2)=(γ_(1,S) *P1)/(γ_(2,S) *P2 in which

-   -   γ_(1,S) represents the activity coefficient of the first        compound 1 in the organic extracting agent under consideration        at infinite dilution,    -   P1 represents the saturating vapor pressure of the first        compound 1,    -   γ_(2,S) represents the activity coefficient of the second        compound 2 of the binary couple in the organic extracting agent        under consideration at infinite dilution,    -   P2 represents the saturating vapor pressure of the second        compound.

An absorption capacity is also calculated for each of the solventsstudied and for a binary couple (1,2) under consideration. Theabsorption capacity is calculated via the formula C_(2,S)=1/(γ_(2,S)) inwhich γ_(2,S) represents the activity coefficient of the second compoundof the binary couple under consideration in said organic extractingagent studied at infinite dilution. The calculations are repeated foreach organic extracting agent studied. Minimum separation factor andabsorption capacity values are identified so as to allow a sufficientseparation between the first compound and the second compound of thebinary couple (1,2) under consideration. The saturating vapor pressureis considered for a temperature of 25° C.

Example

To purify 2,3,3,3-tetrafluoro-1-propene, the binary couple2,3,3,3-tetrafluoro-1-propene/trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) is considered to select the organic extracting agent (seetable 1 below). The mixture to be purified comprises2,3,3,3-tetrafluoro-1-propene, 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E). The extractive distillations are performed with the organicextracting agents having a separation factor of greater than or equal to1.6 and an absorption capacity of greater than or equal to 0.80.2,3,3,3-Tetrafluoro-1-propene was extracted and the content of the otherconstituents is reduced, mainly of trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E).

TABLE 1 capacity and separation factor of the organic extracting agentAbsorption Separation Organic extracting agent capacity factorEthylamine 1.95 2.92 Isopropylamine 1.85 2.56 Diethyl ether 1.48 1.79Dimethoxymethane 1.37 1.95 n-Propylamine 1.86 2.61 Diethylamine 1.571.88 Diisopropyl ether 1.34 1.60 2-Ethoxy-2-methylpropane 1.27 1.62Diethoxymethane 1.41 1.86 Isopropyl acetate 1.42 2.15 3-Pentylamine 1.632.05 2-Methoxyethanamine 1.98 3.19 tert-Butyl acetate 1.37 2.10 Dioxane1.09 2.24 Trimethoxymethane 1.28 2.11 n-Pentylamine 1.64 2.311,3-Dioxane 1.09 2.23 sec-Butyl acetate 1.45 2.12 1,2-Diaminoethane 1.294.43 1-Methoxy-2-propanol 0.86 2.31 n-Butyl acetate 1.35 2.141-Ethoxy-2-propanol 1.12 2.27 Hexanal 1.09 1.98

The invention claimed is:
 1. A process for purifying2,3,3,3-tetrafluoro-1-propene (1234yf) using a first compositioncomprising 2,3,3,3-tetrafluoro-1-propene and at least one compoundselected from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), said process comprising: a) placing said first compositionin contact with at least one organic extracting agent to form a secondcomposition; b) distilling said second composition by extractivedistillation to form: i) a third composition comprising said organicextracting agent and said at least one compound selected from the groupconsisting of 1,1-difluoroethane (152a), chloropentafluoroethane (115)and trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); and ii) a streamcomprising 2,3,3,3-tetrafluoro-1-propene; and c) recovering andseparating said third composition to form a stream comprising saidorganic extracting agent and a stream comprising said at least onecompound selected from the group consisting of 1,1-difluoroethane(152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).
 2. The process asclaimed in claim 1, wherein the first composition comprises2,3,3,3-tetrafluoro-1-propene, trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) and optionally or not at least one compound selected from thegroup consisting of 1,1-difluoroethane (152a) andchloropentafluoroethane (115) and the third composition comprises saidorganic extracting agent, trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E)and optionally or not at least one compound selected from the groupconsisting of 1,1-difluoroethane (152a) and chloropentafluoroethane(115); and wherein step c) comprises recovering said third compositionand separating between, on the one hand, said organic extracting agentand, on the other hand, trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E)and optionally or not at least one compound selected from the groupconsisting of 1,1-difluoroethane (152a) and chloropentafluoroethane(115).
 3. The process as claimed in claim 1, wherein said organicextracting agent comprises a solvent selected from the group consistingof hydrocarbon, halohydrocarbon, alcohol, ketone, amine, ester, ether,aldehyde, nitrile, carbonate, thioalkyl, amide and heterocycle; or saidorganic extracting agent comprises difluorodiethylsilane,triethylfluorosilane or perfluorobutanoic acid.
 4. The process asclaimed in claim 1, wherein the boiling point of said organic extractingagent is between 10 and 150° C.
 5. The process as claimed in claim 1,wherein said organic extracting agent has a separation factor S_(1,2) ofgreater than or equal to 1.1, said separation factor being calculated bythe formula S_(1,2)=(γ_(1,S)*P1)/(γ_(2,S)*P2) wherein γ_(1,S) representsthe activity coefficient of 2,3,3,3-tetrafluoro-1-propene in saidorganic extracting agent at infinite dilution; P1 represents thesaturating vapor pressure of 2,3,3,3-tetrafluoro-1-propene; γ_(2,S)represents the activity coefficient of said at least one compoundselected from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E) in said organic extracting agent at infinite dilution; and P2represents the saturating vapor pressure of said at least one compoundselected from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E).
 6. The process as claimed in claim 1, wherein said organicextracting agent has an absorption capacity C_(2,S) of greater than orequal to 0.20, said absorption capacity being calculated by the formulaC_(2,S)=1/(γ_(2,S)) wherein γ_(2,S) represents the activity coefficientof said at least one compound selected from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) in said organicextracting agent at infinite dilution.
 7. The process as claimed inclaim 1, wherein said first composition comprises an azeotropic orquasi-azeotropic composition comprising 2,3,3,3-tetrafluoro-1-propene,trans-1,3,3,3-tetrafluoro-1-propene (1234ze-E) and optionally or not atleast one compound selected from the group consisting of1,1-difluoroethane (152a) and chloropentafluoroethane (115).
 8. Theprocess as claimed in claim 1, wherein said organic extracting agent isselected from the group consisting of ethylamine, isopropylamine,diethyl ether, ethoxyethene, dimethoxymethane, n-propylamine, methylt-butyl ether, diethylamine, propanone, methyl acetate, isobutanal,tetrahydrofuran, isopropyl formate, diisopropyl ether,2-ethoxy-2-methylpropane, ethyl acetate, butanone, diethoxymethane,isopropyl acetate, 3-pentylamine, 2-methoxyethanamine, tert-butylacetate, dioxane, 3-pentanone, 1,1-diethoxyethane, 2-pentanone,trimethoxymethane, n-pentylamine, 1,3-dioxane, 3,3-dimethyl-2-butanone,sec-butyl acetate, 4-methyl-2-pentanone, 1,2-diaminoethane,1-methoxy2-propanol, diethyl carbonate, n-butyl acetate,1-ethoxy-2-propanol and hexanal.
 9. The process as claimed in claim 1,further comprising recovering the stream comprising2,3,3,3-tetrafluoro-1-propene formed in step b) and freeing said streamof at least one compound selected from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E).
 10. The process asclaimed in claim 1, further comprising, prior to step a): i′) use of acomposition comprising 2,3,3,3-tetrafluoro-1-propene, impurities with aboiling point below the boiling point of 2,3,3,3-tetrafluoro-1-propene,and at least one compound selected from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E), and optionally heavyimpurities; ii′) distilling said composition from step i) to remove, atthe top of the column, impurities with a boiling point below the boilingpoint of 2,3,3,3-tetrafluoro-1-propene and to form a first streamcomprising 2,3,3,3-tetrafluoro-1-propene and at least one compoundselected from the group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), and optionally heavy impurities, recovered at the bottom ofthe distillation column; and iii′) optionally, distillating said firststream recovered at the bottom of the distillation column in step ii′)to recover, at the top of the column, a second stream comprising2,3,3,3-tetrafluoro-1-propene and at least one compound selected fromthe group consisting of 1,1-difluoroethane (152a),chloropentafluoroethane (115) and trans-1,3,3,3-tetrafluoro-1-propene(1234ze-E), and, at the bottom of the distillation column, a streamcomprising the heavy impurities; wherein said first stream recovered instep ii′) or said second stream recovered in step iii′) corresponds tosaid first composition used in step a).
 11. A process for producing andpurifying 2,3,3,3-tetrafluoro-1-propene, comprising: A) fluorination inthe presence of a catalyst for a compound of formula (I)CX(Y)2-CX(Y)_(m)—CH_(m)XY wherein X and Y independently represent ahydrogen, fluorine or chlorine atom and m=0 or 1; and/or fluorination inthe presence of a catalyst for a compound of formula(CX_(n)Y_(3-n))CH_(p)X_(1-p)CH_(m)X_(2-m) (II) in which X is,independently of each other, Cl, F, I or Br; Y is, independently of eachother, H, Cl, F, I or Br; n is 1, 2 or 3; and m is 0, 1 or 2; and p is 0or 1; B) recovering a stream comprising 2,3,3,3-tetrafluoro-1-propeneand at least one compound selected from the group consisting of1,1-difluoroethane (152a), chloropentafluoroethane (115) andtrans-1,3,3,3-tetrafluoro-1-propene (1234ze-E); C) implementing theprocess as claimed in claim 1 using the stream recovered in step B).